View Filing Data

Print Document View Excel Document

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2013	Feb. 20, 2014	Jun. 28, 2013
Entity Registrant Name	BRANDYWINE REALTY TRUST
Entity Central Index Key	0000790816
Document Type	10-K
Document Period End Date	Dec. 31, 2013
Amendment Flag	false
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q4
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 2,091,192,105
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		156,738,955
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Entity Registrant Name	BRANDYWINE OPERATING PARTNERSHIP, L.P.
Entity Central Index Key	0001060386
Document Type	10-K
Document Period End Date	Dec. 31, 2013
Amendment Flag	false
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q4
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue:
Rents	$ 461,387	$ 437,560	$ 441,329
Tenant reimbursements	79,087	77,060	77,404
Termination Fees	4,497	3,233	2,951
Third party management fees, labor reimbursement and leasing	13,053	12,116	11,536
Other	4,186	5,710	5,348
Total revenue	562,210	535,679	538,568
Operating Expenses:
Property operating expenses	160,406	152,319	159,768
Real estate taxes	55,612	53,402	51,433
Third party management expenses	5,751	5,127	5,590
Depreciation and amortization	197,021	188,382	202,933
General and administrative expenses	27,628	25,413	24,602
Total operating expenses	446,418	424,643	444,326
Operating income	115,792	111,036	94,242
Other Income (Expense):
Interest income	1,044	3,008	1,810
Historic tax credit transaction income	11,853	11,840	12,026
Interest expense	(121,937)	(132,939)	(131,405)
Interest expense - amortization of deferred financing costs	(4,676)	(6,208)	(4,991)
Interest expense — financing obligation	(972)	(850)	0
Recognized hedge activity	0	(2,985)	0
Equity in income of real estate ventures	3,664	2,741	3,775
Net gain from remeasurement of investments in real estate ventures	6,866	0	0
Net gain on sale of interests in real estate	0	0	2,985
Net gain (loss) on sale of undepreciated real estate	(137)	0	0
Net gain (loss) on real estate venture transactions	29,604	(950)	(222)
Gain (loss) on early extinguishment of debt	(2,119)	(22,002)	(2,776)
Income (loss) from continuing operations	38,982	(37,309)	(24,556)
Discontinued operations:
Income from discontinued operations	825	9,064	12,794
Net gain (loss) on disposition of discontinued operations	3,382	34,774	7,047
Total discontinued operations	4,207	43,838	19,841
Net income (loss)	43,189	6,529	(4,715)
Net income from discontinued operations attributable to non-controlling interests - LP units	(55)	(797)	(778)
Net (income) loss attributable to non-controlling interests — LP units	357	(863)	(994)
Net (income) loss attributable to non-controlling interests	(412)	66	216
Net income (loss)	42,777	6,595	(4,499)
Distribution to Preferred Shares	(6,900)	(10,405)	(7,992)
Preferred share/unit redemption charge	0	(4,052)	0
Amount allocated to unvested restricted shareholders	(363)	(376)	(505)
Net income (loss) attributable to Common Shareholders/Unitholders	$ 35,514	$ (8,238)	$ (12,996)
Basic income (loss) per Common Share/Unit:
Continuing operations (in dollars per share)	$ 0.20	$ (0.36)	$ (0.24)
Discontinued operations (in dollars per share)	0.03	0.30	0.14
Basic income (loss) per Common Share (in dollars per share)	0.23	(0.06)	(0.10)
Diluted income (loss) per Common Share/Unit:
Continuing operations (in dollars per share)	0.20	(0.36)	(0.24)
Discontinued operations (in dollars per share)	0.03	0.30	0.14
Diluted income (loss) per Common Share/Unit (in dollars per share)	$ 0.23	$ (0.06)	$ (0.10)
Basic weighted average shares outstanding (in shares)	153,140,458	143,257,097	135,444,424
Diluted weighted average shares outstanding (in shares)	154,414,311	143,257,097	135,444,424
Net income (loss)
Income (loss) from continuing operations	$ 38,625	$ (36,446)	$ (23,562)
Income (loss) from discontinued operations	4,152	43,041	19,063
Net income (loss)	42,777	6,595	(4,499)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue:
Rents	461,387	437,560	441,329
Tenant reimbursements	79,087	77,060	77,404
Termination Fees	4,497	3,233	2,951
Third party management fees, labor reimbursement and leasing	13,053	12,116	11,536
Other	4,186	5,710	5,348
Total revenue	562,210	535,679	538,568
Operating Expenses:
Property operating expenses	160,406	152,319	159,768
Real estate taxes	55,612	53,402	51,433
Third party management expenses	5,751	5,127	5,590
Depreciation and amortization	197,021	188,382	202,933
General and administrative expenses	27,628	25,413	24,602
Total operating expenses	446,418	424,643	444,326
Operating income	115,792	111,036	94,242
Other Income (Expense):
Interest income	1,044	3,008	1,810
Historic tax credit transaction income	11,853	11,840	12,026
Interest expense	(121,937)	(132,939)	(131,405)
Interest expense - amortization of deferred financing costs	(4,676)	(6,208)	(4,991)
Interest expense — financing obligation	(972)	(850)	0
Recognized hedge activity	0	(2,985)	0
Equity in income of real estate ventures	3,664	2,741	3,775
Net gain from remeasurement of investments in real estate ventures	6,866	0	0
Net gain on sale of interests in real estate	0	0	2,985
Net gain (loss) on sale of undepreciated real estate	(137)	0	0
Net gain (loss) on real estate venture transactions	29,604	(950)	(222)
Gain (loss) on early extinguishment of debt	(2,119)	(22,002)	(2,776)
Income (loss) from continuing operations	38,982	(37,309)	(24,556)
Discontinued operations:
Income from discontinued operations	825	9,064	12,794
Net gain (loss) on disposition of discontinued operations	3,382	34,774	7,047
Total discontinued operations	4,207	43,838	19,841
Net income (loss)	43,189	6,529	(4,715)
Net income (loss)	43,189	6,529	(4,715)
Distribution to Preferred Shares	(6,900)	(10,405)	(7,992)
Preferred share/unit redemption charge	0	(4,052)	0
Amount allocated to unvested restricted shareholders	(363)	(376)	(505)
Net income (loss) attributable to Common Shareholders/Unitholders	$ 35,926	$ (8,304)	$ (13,212)
Basic income (loss) per Common Share/Unit:
Continuing operations (in dollars per share)	$ 0.20	$ (0.36)	$ (0.23)
Discontinued operations (in dollars per share)	0.03	0.30	0.14
Basic income (loss) per Common Share (in dollars per share)	0.23	(0.06)	(0.09)
Diluted income (loss) per Common Share/Unit:
Continuing operations (in dollars per share)	0.20	(0.36)	(0.23)
Discontinued operations (in dollars per share)	0.03	0.30	0.14
Diluted income (loss) per Common Share/Unit (in dollars per share)	$ 0.23	$ (0.06)	$ (0.09)
Basic weighted average shares outstanding (in shares)	154,929,545	145,883,217	145,118,841
Diluted weighted average shares outstanding (in shares)	156,203,398	145,883,217	145,118,841
Net income (loss)
Income (loss) from continuing operations	$ 38,982	$ (37,309)	$ (24,556)
Income (loss) from discontinued operations	4,207	43,838	19,841
Net income (loss)	$ 43,189	$ 6,529	$ (4,715)

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Real estate investments:
Operating properties	$ 4,669,289	$ 4,726,169
Accumulated depreciation	(983,808)	(954,665)
Operating real estate investments, net	3,685,481	3,771,504
Construction-in-progress	74,174	48,950
Land inventory	93,351	102,439
Total real estate investments, net	3,853,006	3,922,893
Cash and cash equivalents	263,207	1,549
Accounts receivable, net	17,389	13,232
Accrued rent receivable, net	126,295	122,066
Investment in real estate ventures, at equity	180,512	193,555
Deferred costs, net	122,954	122,243
Intangible assets, net	132,329	70,620
Notes receivable	7,026	7,226
Other Assets	62,377	53,325
Total assets	4,765,095	4,506,709
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	670,151	442,974
Unsecured credit facility	0	69,000
Unsecured term loans	450,000	450,000
Unsecured senior notes, net of discounts	1,475,230	1,503,356
Accounts payable and accrued expenses	83,693	71,579
Distributions payable	25,584	23,652
Deferred income, gains and rent	71,635	82,947
Acquired lease intangibles, net	34,444	33,859
Other liabilities	32,923	55,826
Total liabilities	2,843,660	2,733,193
Commitments and contingencies (Note 20)
Brandywine Realty Trust's equity:
6.90% Series E Preferred Shares/Units; issued and outstanding- 4,000,000 in 2013 and 2012	40	40
Common Shares of Brandywine Realty Trust’s beneficial interest, $0.01 par value; shares authorized 200,000,000; 156,731,993 and 143,538,733 issued and outstanding in 2013 and 2012, respectively	1,566	1,434
Additional paid-in capital	2,971,596	2,780,194
Deferred compensation payable in common shares	5,407	5,352
Common shares in grantor trust, 312,280 in 2013 and 290,745 in 2012	(5,407)	(5,352)
Cumulative earnings	522,528	479,734
Accumulated other comprehensive loss	(2,995)	(15,918)
Cumulative distributions	(1,592,515)	(1,493,206)
Total equity, excluding non-controlling interests	1,900,220	1,752,278
Non-controlling interests	21,215	21,238
Total equity	1,921,435	1,773,516
Total liabilities and equity	4,765,095	4,506,709
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Operating properties	4,669,289	4,726,169
Accumulated depreciation	(983,808)	(954,665)
Operating real estate investments, net	3,685,481	3,771,504
Construction-in-progress	74,174	48,950
Land inventory	93,351	102,439
Total real estate investments, net	3,853,006	3,922,893
Cash and cash equivalents	263,207	1,549
Accounts receivable, net	17,389	13,232
Accrued rent receivable, net	126,295	122,066
Investment in real estate ventures, at equity	180,512	193,555
Deferred costs, net	122,954	122,243
Intangible assets, net	132,329	70,620
Notes receivable	7,026	7,226
Other Assets	62,377	53,325
Total assets	4,765,095	4,506,709
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	670,151	442,974
Unsecured credit facility	0	69,000
Unsecured term loans	450,000	450,000
Unsecured senior notes, net of discounts	1,475,230	1,503,356
Accounts payable and accrued expenses	83,693	71,579
Distributions payable	25,584	23,652
Deferred income, gains and rent	71,635	82,947
Acquired lease intangibles, net	34,444	33,859
Other liabilities	32,923	55,826
Total liabilities	2,843,660	2,733,193
Commitments and contingencies (Note 20)
Redeemable limited partnership units at redemption value;
Redeemable limited partnership units at redemption value; 1,763,739 and 1,845,737 issued and outstanding in 2013 and 2012, respectively	26,486	26,777
Brandywine Realty Trust's equity:
6.90% Series E Preferred Shares/Units; issued and outstanding- 4,000,000 in 2013 and 2012	96,850	96,850
General Partnership Capital, 156,731,993 and 143,538,733 units issued and outstanding in 2013 and 2012, respectively	1,800,530	1,666,341
Accumulated other comprehensive loss	(3,377)	(16,452)
Total equity, excluding non-controlling interests	1,894,003	1,746,739
Non-controlling interests	946	0
Total equity	1,894,949	1,746,739
Total liabilities and equity	4,765,095	4,506,709
7.375% Series D Preferred Shares \| BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Total equity	0	0
6.90% Series E Preferred Stock [Member]
Brandywine Realty Trust's equity:
Total equity	40	40
6.90% Series E Preferred Stock [Member] \| BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Total equity	0	0
Series E-linked Preferred Stock [Member] \| BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
6.90% Series E Preferred Shares/Units; issued and outstanding- 4,000,000 in 2013 and 2012		96,850
Total equity	96,850	96,850
Noncontrolling Interest [Member]
Brandywine Realty Trust's equity:
Total equity	21,215	21,238
Noncontrolling Interest [Member] \| BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Total equity	$ 946	$ 0

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Preferred Stock, Value, Issued	$ 40	$ 40
Brandywine Realty Trust's equity:
Preferred shares, shares authorized	20,000,000	20,000,000
Preferred shares, dividend rate (as a percent)	6.90%
Preferred shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares, shares issued	4,000,000	4,000,000
Preferred shares, shares outstanding	4,000,000	4,000,000
Common shares in grantor trust	$ 0.01	$ 0.01
Common shares of Brandywine Realty Trust's beneficial interest, shares authorized	200,000,000	200,000,000
Common shares of Brandywine Realty Trust's beneficial interest, shares issued	156,703,790	143,538,733
Common shares of Brandywine Realty Trust's beneficial interest, shares outstanding	156,703,790	143,538,733
Common shares in grantor trust	313,023	290,745
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Preferred Stock, Value, Issued	$ 96,850	$ 96,850
Brandywine Realty Trust's equity:
Preferred shares, dividend rate (as a percent)	6.90%
Preferred shares, shares issued	4,000,000	4,000,000
Preferred shares, shares outstanding	4,000,000	4,000,000
Redeemable Limited Partnership, units issued	1,763,739	1,845,737
Redeemable Limited Partnership, units outstanding	1,763,739	1,845,737
General Partners' Capital account, units issued	156,703,790	143,538,733
General Partners' Capital account, units outstanding	156,703,790	143,538,733

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income (loss)	$ 43,189	$ 6,529	$ (4,715)
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments	12,789	(7,338)	(4,499)
Settlement of interest rate swaps	0	(2,985)	0
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	286	297	153
Total comprehensive income (loss)	13,075	(10,026)	(4,346)
Comprehensive income (loss)	56,264	(3,497)	(9,061)
Comprehensive (income) loss attributable to non-controlling interest	(564)	261	427
Comprehensive income (loss) attributable to Brandywine Realty Trust	55,700	(3,236)	(8,634)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Net income (loss)	43,189	6,529	(4,715)
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments	12,789	(7,338)	(4,499)
Settlement of interest rate swaps	0	(2,985)	0
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	286	297	153
Total comprehensive income (loss)	13,075	(10,026)	(4,346)
Comprehensive income (loss)	$ 56,264	$ (3,497)	$ (9,061)

Consolidated Statements of Beneficiaries' Equity - USD ($) $ in Thousands	Total	Series E Preferred Stock [Member]	Common Stock	Treasury Stock	Deferred Compensation Payable in Common Shares	Common Shares in Grantor Trust	Additional Paid-in Capital	Cumulative Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Distributions	Non-Controlling Interests	Subsidiaries [Member]	Subsidiaries [Member] Series E Preferred Stock [Member]	Subsidiaries [Member] Accumulated Other Comprehensive Income (Loss)	Subsidiaries [Member] Non-Controlling Interests	Subsidiaries [Member] Series D Preferred Stock [Member]	Subsidiaries [Member] Total partners equity [Member]	Subsidiaries [Member] Series E-linked Preferred Stock [Member]
Beginning Balance, shares at Dec. 31, 2010		4,300,000	134,601,796	116,679	291,281								2,300,000			2,000,000		0
Beginning Balance at Dec. 31, 2010	$ 1,977,774	$ 43	$ 1,343	$ (3,074)	$ 5,774	$ (5,774)	$ 2,671,217	$ 483,439	$ (1,945)	$ (1,301,521)	$ 128,272		$ 55,538	$ (2,080)	$ 0	$ 47,912	$ 1,844,919	$ 0
Net income (loss)	(4,715)							(4,500)			(215)	$ (4,715)					(4,715)
Comprehensive income (loss)	(4,346)								(4,134)		(212)	(4,346)		(4,346)			(4,346)
Issuance of Common Shares of Beneficial Interest, shares			679,285
Issuance of Common Shares of Beneficial Interest	8,272		$ 7				8,265
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(377)						(345)				(32)
Conversion of LP Units to Common Shares	0		$ 72				85,966				(86,038)						86,038
Conversion of LP Units to Common Shares, shares			7,204,104
Bonus Share Issuance, shares				(463)	463
Bonus Share Issuance	6			$ 12	$ 6	(6)		(6)									6
Vesting of Restricted Shares, shares			85,248	(116,216)	9,043
Vesting of Restricted Shares, Value	(350)		$ 1	$ 3,062			(1,818)	(1,595)									(352)
Restricted Share Amortization	2,937						2,937										2,937
Restricted Performance Units Amortization	1,679						1,679										1,679
Exercise of Stock Options, shares			120,179
Exercise of Stock Options	350		$ 1				349										350
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition							1,487
Share Issuance from/to Deferred Compensation Plan, shares			(845)		(8,141)
Share Issuance from/to Deferred Compensation Plan	(16)				$ (149)	149	(16)
Share Option Amortization	1,487																1,487
Outperformance Plan Amortization	123						123										123
Share Choice Plan Issuance Value	(55)						(55)										(55)
Share Choice Plan Issuance Shares			(1,684)
Stock Issued During Period, Shares, Other			2,672
Stock Issued During Period, Value, Other	32						32
Adjustment to Non-controlling Interest	0						6,376				(6,376)
Preferred Share distributions	(7,992)									(7,992)							(7,992)
Preferred share/unit redemption charge	0											0
Distributions declared ($0.60) per share in each of 2013, 2012, and 2011	(85,113)									(82,819)	(2,294)
Ending Balance, shares at Dec. 31, 2011		4,300,000	142,690,755	0	292,646								2,300,000			2,000,000		0
Ending Balance at Dec. 31, 2011	1,889,696	$ 43	$ 1,424	$ 0	$ 5,631	(5,631)	2,776,197	477,338	(6,079)	(1,392,332)	33,105		$ 55,538	(6,426)	0	$ 47,912	1,851,326	$ 0
Net income (loss)	6,529							6,595			(66)	6,529					6,529
Comprehensive income (loss)	(10,026)								(9,839)		(187)	(10,026)		(10,026)			(10,026)
Issuance of Common Shares of Beneficial Interest, shares		4,000,000
Issuance of Common Shares of Beneficial Interest	96,850	$ 40					96,810
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(613)						(613)										(613)
Conversion of LP Units to Common Shares	(167)		$ 1				149	(49)			(268)						(49)
Conversion of LP Units to Common Shares, shares			20,464
Redemption of preferred shares, Shares		(4,300,000)											(2,300,000)			(2,000,000)
Redemption of preferred shares, Value	(103,448)	$ (43)					(103,405)						$ 55,538			$ 47,912	103,450
Bonus Share Issuance, shares			35,703
Bonus Share Issuance	387						387										387
Partners' Capital Account, Redemptions	(9,741)							(4,185)			(5,556)						9,741
Vesting of Restricted Shares, shares			293,614		9,036
Vesting of Restricted Shares, Value	(1,385)		$ 4				(1,389)										(1,385)
Restricted Share Amortization	3,271						3,271										3,271
Stock Issued During Period, Shares, Vesting of restricted performance units			272,131
Stock Issued During Period, Value, Vesting of restricted performance units	(1,495)		$ 3				(1,498)										(1,495)
Restricted Performance Units Amortization	3,379						3,379										3,379
Restricted Stock Award, Forfeitures	35							35									(35)
Exercise of Stock Options, shares			230,294
Exercise of Stock Options	976		$ 2				974										976
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition							1,636
Share Issuance from/to Deferred Compensation Plan, shares			(5,564)		(10,937)
Share Issuance from/to Deferred Compensation Plan	0				$ (279)	279
Share Option Amortization	1,636																1,636
Stock Issued During Period, Shares, Other			1,336
Stock Issued During Period, Value, Other	15						15
Adjustment to Non-controlling Interest	0						4,281				(4,281)
Preferred Share distributions	(10,405)									(10,405)							(10,405)
Preferred share/unit redemption charge	(4,052)									(4,052)		(4,052)					(4,052)
Distributions declared ($0.60) per share in each of 2013, 2012, and 2011	(87,926)									(86,417)	(1,509)
Ending Balance, shares at Dec. 31, 2012		4,000,000	143,538,733	0	290,745								0			0		4,000,000
Ending Balance at Dec. 31, 2012	$ 1,773,516	$ 40	$ 1,434	$ 0	$ 5,352	(5,352)	2,780,194	479,734	(15,918)	(1,493,206)	21,238	$ 1,746,739	$ 0	(16,452)	0	$ 0	1,746,739	$ 96,850
Preferred Stock, Shares Issued	4,000,000											4,000,000						4,000,000
Net income (loss)	$ 43,189							42,777			412	$ 43,189					43,189
Comprehensive income (loss)	13,075								12,923		152	13,075		13,075			13,075
Issuance of Common Shares of Beneficial Interest, shares			12,650,000
Issuance of Common Shares of Beneficial Interest	182,034		$ 127				181,907
Noncontrolling Interest, Increase from Business Combination	946										946				(946)		(946)
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(744)						(744)
Conversion of LP Units to Common Shares	0		$ 1				1,239				(1,240)						1,240
Conversion of LP Units to Common Shares, shares			81,998
Redemption of preferred shares, Value																	(361)
Bonus Share Issuance, shares			27,918
Bonus Share Issuance	361						361										(902)
Partners' Capital Account, Redemptions																	(17)
Vesting of Restricted Shares, shares			147,495		7,050
Vesting of Restricted Shares, Value	(902)		$ 2				(904)
Restricted Share Amortization	3,079						3,079										3,079
Stock Issued During Period, Shares, Vesting of restricted performance units			53,134		27,067
Stock Issued During Period, Value, Vesting of restricted performance units	(159)		$ 1				(160)
Restricted Performance Units Amortization	4,333						4,333										4,333
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	$ (17)							17
Exercise of Stock Options, shares	236,318		236,318
Exercise of Stock Options	$ 2,380		$ 1				2,379										2,380
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition							670
Share Issuance from/to Deferred Compensation Plan, shares			(5,012)		(12,583)
Share Issuance from/to Deferred Compensation Plan	0				$ 55	(55)
Share Option Amortization	670																670
Share Choice Plan Issuance Value																	(160)
Stock Issued During Period, Shares, Other			1,409
Stock Issued During Period, Value, Other	20						20
Adjustment to Non-controlling Interest	0						(778)				778
Preferred Share distributions	(6,900)									(6,900)							6,900
Preferred share/unit redemption charge	0											0
Distributions declared ($0.60) per share in each of 2013, 2012, and 2011	(93,480)									(92,409)	(1,071)
Ending Balance, shares at Dec. 31, 2013		4,000,000	156,731,993		312,279								0			0		4,000,000
Ending Balance at Dec. 31, 2013	$ 1,921,435	$ 40	$ 1,566		$ 5,407	$ (5,407)	$ 2,971,596	$ 522,528	$ (2,995)	$ (1,592,515)	$ 21,215	$ 1,894,949	$ 0	$ (3,377)	$ 946	$ 0	$ 1,894,949	$ 96,850
Preferred Stock, Shares Issued	4,000,000											4,000,000

Consolidated Statements of Beneficiaries' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Distributions Declared, Per Share	$ 0.60	$ 0.60	$ 0.60
Cumulative Distributions
Distributions Declared, Per Share	0.15	0.15	0.60
Non-Controlling Interests
Distributions Declared, Per Share	$ 0.15	$ 0.15	$ 0.60

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income (loss)	$ 43,189	$ 6,529	$ (4,715)
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation and amortization	198,731	198,579	219,110
Amortization of deferred financing costs	4,676	6,208	4,991
Amortization of debt discount/(premium), net	2,480	1,760	1,567
Amortization of stock compensation costs	6,998	5,685	5,282
Share-based compensation expense relating to awards withheld for employee taxes upon vesting of share awards	(1,062)	(2,493)	(1,012)
Recognized hedge activity	0	2,985	0
Straight-line rent income	(20,136)	(23,566)	(20,298)
Amortization of above (below) Market Leases, Net	(7,170)	(6,084)	(5,384)
Straight-line ground rent expense	1,509	1,897	1,924
Provision for doubtful accounts	2,467	2,198	1,924
Net gain on sale of interests in real estate	(29,166)	(34,774)	(10,008)
Loss on real estate venture formation	0	950	222
Net gain from remeasurement of investments in real estate ventures	6,866	0	0
Net gain on real estate venture transactions	(3,683)	0	0
Loss on early extinguishment of debt	2,119	22,002	2,776
Historic tax credit transaction income	(11,853)	(11,840)	(12,026)
Real estate venture income in excess of distributions	(2,014)	(1,517)	(1,175)
Cumulative interest accretion of repayments of unsecured notes	0	0	(4,005)
Contributions from historic tax credit transaction, net of deferred costs	0	0	2,694
Deferred financing obligation	(974)	(1,803)	0
Changes in assets and liabilities:
Accounts receivable	(4,048)	262	(856)
Other assets	5,440	4,244	(3,851)
Accounts payable and accrued expenses	(526)	(8,355)	7,732
Deferred income, gains and rent	3,758	(2,167)	(7,220)
Other liabilities	(385)	(1,590)	(425)
Net cash from operating activities	183,484	159,110	177,247
Cash flows from investing activities:
Acquisition of properties	(161,604)	(77,555)	(40,674)
Investments in Available-for-sale Securities, Debt	0	(105,250)	0
Proceeds from the sale of available-for-sale securities	0	105,250	0
Sales of properties, net	423,480	170,918	155,956
Distribution of sales proceeds of real estate ventures	16,963	0	0
Proceeds from repayment of mortgage notes receivable	200	23,364	0
Capital expenditures for tenant improvements	(109,357)	(86,986)	(130,482)
Capital expenditures for redevelopments	(6,265)	(11,964)	(674)
Capital expenditures for developments	(5,490)	(162)	0
Payments for (Proceeds from) Other Investing Activities	1,976	0	0
Advances for purchase of tenant assets, net of repayments	(127)	270	1,365
Loan proceeds from an unconsolidated Real Estate Venture partner	0	566	1,388
Loan provided to unconsolidated Real Estate Venture partner	0	0	(1,122)
Investment in unconsolidated Real Estate Ventures	(33,069)	(65,354)	(5,277)
Increase (Decrease) in Restricted Cash	1,902	(1,827)	1,502
Cash distributions from unconsolidated Real Estate Ventures in excess of cumulative equity income	7,496	5,109	10,316
Leasing costs	(31,397)	(31,243)	(38,461)
Net cash from (used in) investing activities	104,708	(74,864)	(46,163)
Cash flows from financing activities:
Proceeds from New Unsecured Term Loans	0	600,000	0
Proceeds from Credit Facility	186,000	90,500	706,002
Repayments of Credit Facility	(255,000)	(297,000)	(613,502)
Repayments of mortgage notes payable	(11,268)	(68,513)	(221,856)
Proceeds from unsecured notes	0	248,183	321,448
Deferred financing obligation interest expense	0	935	0
Net Proceeds from Issuance of Common Stock	181,527	0	7,930
Net Proceeds from Issuance of Preferred Stock and Preference Stock	0	96,237	0
Redemption of preferred units	0	(108,536)	0
Cash used in redemption of partnership units	0	(9,676)	0
Repayments from unsecured notes	(31,369)	(338,097)	(105,381)
Repayments of unsecured term loan	0	(190,485)	(145,500)
Net settlement of hedge transactions	0	0	(613)
Debt financing costs	(355)	(10,128)	(4,249)
Exercise of stock options	2,381	976	350
Distributions paid to shareholders/unitholders	(97,367)	(96,030)	(89,559)
Distributions to noncontrolling interest	(1,083)	(1,473)	(2,309)
Net cash from (used in) financing activities	(26,534)	(83,107)	(147,239)
Increase (decrease) in cash and cash equivalents	261,658	1,139	(16,155)
Cash and cash equivalents at beginning of period	1,549	410	16,565
Cash and cash equivalents at end of period	263,207	1,549	410
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2013, 2012, and 2011 of $3,137, $2,560, and $1,997, respectively	118,714	137,823	135,210
Supplemental disclosure of non-cash activity:
Change in operating real estate related to a non-cash acquisition of an operating property	(21,649)	0	0
Change in intangible assets, net related to non-cash acquisition of an operating property	(3,517)	0	0
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	462	0	0
Change in investments in joint venture related to non-cash acquisition of property	13,040	0	0
Change in investments in joint venture related to non-cash disposition of property	(17,628)	0	0
Change in operating real estate related to non-cash adjustment to land	7,752	0	0
Change in mortgage notes payable related to acquisition of an operating property	238,082	0	0
Change in investments in joint venture related to a contribution of land at period end	(6,058)	(15,222)	0
Change in investments in joint venture related to a contribution of services	0	(711)	0
Change in capital expenditures financed through accounts payable at period end	11,703	7,059	(3,896)
Change in capital expenditures financed through retention payable at period end	(204)	566	(6,213)
Change in unfunded tenant allowance	(969)	(1,089)	(1,717)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income (loss)	43,189	6,529	(4,715)
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation and amortization	198,731	198,579	219,110
Amortization of deferred financing costs	4,676	6,208	4,991
Amortization of debt discount/(premium), net	2,480	1,760	1,567
Amortization of stock compensation costs	6,998	5,685	5,282
Share-based compensation expense relating to awards withheld for employee taxes upon vesting of share awards	(1,062)	(2,493)	(1,012)
Recognized hedge activity	0	2,985	0
Straight-line rent income	(20,136)	(23,566)	(20,298)
Amortization of above (below) Market Leases, Net	(7,170)	(6,084)	(5,384)
Straight-line ground rent expense	1,509	1,897	1,924
Provision for doubtful accounts	2,467	2,198	1,924
Net gain on sale of interests in real estate	(29,166)	(34,774)	(10,008)
Loss on real estate venture formation	0	950	222
Net gain from remeasurement of investments in real estate ventures	6,866	0	0
Net gain on real estate venture transactions	(3,683)	0	0
Loss on early extinguishment of debt	2,119	22,002	2,776
Historic tax credit transaction income	(11,853)	(11,840)	(12,026)
Real estate venture income in excess of distributions	(2,014)	(1,517)	(1,175)
Cumulative interest accretion of repayments of unsecured notes	0	0	(4,005)
Contributions from historic tax credit transaction, net of deferred costs	0	0	2,694
Deferred financing obligation	(974)	(1,803)	0
Changes in assets and liabilities:
Accounts receivable	(4,048)	262	(856)
Other assets	5,440	4,244	(3,851)
Accounts payable and accrued expenses	(526)	(8,355)	7,732
Deferred income, gains and rent	3,758	(2,167)	(7,220)
Other liabilities	(385)	(1,590)	(425)
Net cash from operating activities	183,484	159,110	177,247
Cash flows from investing activities:
Acquisition of properties	(161,604)	(77,555)	(40,674)
Investments in Available-for-sale Securities, Debt	0	(105,250)	0
Proceeds from the sale of available-for-sale securities	0	105,250	0
Sales of properties, net	423,480	170,918	155,956
Distribution of sales proceeds of real estate ventures	16,963	0
Proceeds from repayment of mortgage notes receivable	200	23,364	0
Capital expenditures for tenant improvements	(109,357)	(86,986)	(130,482)
Capital expenditures for redevelopments	(6,265)	(11,964)	(674)
Capital expenditures for developments	(5,490)	(162)	0
Payments for (Proceeds from) Other Investing Activities	1,976	0
Advances for purchase of tenant assets, net of repayments	(127)	270	1,365
Loan proceeds from an unconsolidated Real Estate Venture partner	0	566	1,388
Loan provided to unconsolidated Real Estate Venture partner	0	0	(1,122)
Investment in unconsolidated Real Estate Ventures	(33,069)	(65,354)	(5,277)
Increase (Decrease) in Restricted Cash	1,902	(1,827)	1,502
Cash distributions from unconsolidated Real Estate Ventures in excess of cumulative equity income	7,496	5,109	10,316
Leasing costs	(31,397)	(31,243)	(38,461)
Net cash from (used in) investing activities	104,708	(74,864)	(46,163)
Cash flows from financing activities:
Proceeds from New Unsecured Term Loans	0	600,000	0
Proceeds from Credit Facility	186,000	90,500	706,002
Repayments of Credit Facility	(255,000)	(297,000)	(613,502)
Repayments of mortgage notes payable	(11,268)	(68,513)	(221,856)
Proceeds from unsecured notes	0	248,183	321,448
Deferred financing obligation interest expense	0	935	0
Net Proceeds from Issuance of Common Stock	181,527	0	7,930
Net Proceeds from Issuance of Preferred Stock and Preference Stock	0	96,237	0
Redemption of preferred units	0	(108,536)	0
Cash used in redemption of partnership units	0	(9,676)	0
Repayments from unsecured notes	(31,369)	(338,097)	(105,381)
Repayments of unsecured term loan	0	(190,485)	(145,500)
Net settlement of hedge transactions	0	0	(613)
Debt financing costs	(355)	(10,128)	(4,249)
Refund Of Deferred Financing Costs Related To Forward Commitment	0	0	0
Exercise of stock options	2,381	976	350
Distributions paid to shareholders/unitholders	(98,450)	(97,503)	(91,868)
Net cash from (used in) financing activities	(26,534)	(83,107)	(147,239)
Increase (decrease) in cash and cash equivalents	261,658	1,139	(16,155)
Cash and cash equivalents at beginning of period	1,549	410	16,565
Cash and cash equivalents at end of period	263,207	1,549	410
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2013, 2012, and 2011 of $3,137, $2,560, and $1,997, respectively	118,714	137,823	135,210
Supplemental disclosure of non-cash activity:
Change in operating real estate related to a non-cash acquisition of an operating property	(21,649)	0
Change in intangible assets, net related to non-cash acquisition of an operating property	(3,517)	0
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	462	0
Change in investments in joint venture related to non-cash acquisition of property	13,040	0
Change in investments in joint venture related to non-cash disposition of property	(17,628)	0
Change in operating real estate related to non-cash adjustment to land	7,752	0
Change in mortgage notes payable related to acquisition of an operating property	238,082	0	0
Change in investments in joint venture related to a contribution of land at period end	(6,058)	(15,222)
Change in investments in joint venture related to a contribution of services	0
Change in capital expenditures financed through accounts payable at period end	11,703	7,059	(3,896)
Change in capital expenditures financed through retention payable at period end	(204)	566	(6,213)
Change in unfunded tenant allowance	$ (969)	$ (1,089)	$ (1,717)

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental disclosure:
Capitalized interest	$ 2,012	$ 2,560	$ 1,997
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Supplemental disclosure:
Capitalized interest	$ 2,012	$ 2,560	$ 1,997

Consolidated Statement of Partners' Equity - USD ($) $ in Thousands	Total	BRANDYWINE OPERATING PARTNERSHIP, L.P.	Series D Preferred Stock [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Series E Preferred Stock [Member]	Series E Preferred Stock [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Series E-linked Preferred Stock [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	General Partner [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Noncontrolling Interest [Member]	Noncontrolling Interest [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Total partners equity [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.
Beginning Balance at Dec. 31, 2010	$ 1,977,774		$ 47,912	$ 43	$ 55,538	$ 0	$ 1,743,549	$ (1,945)	$ (2,080)	$ 128,272	$ 0	$ 1,844,919
Beginning Balance, shares at Dec. 31, 2010			2,000,000	4,300,000	2,300,000	0	134,485,117
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(4,715)	$ (4,715)					$ (4,715)			(215)		(4,715)
Comprehensive income (loss)	(4,346)	(4,346)						(4,134)	(4,346)	(212)		(4,346)
Deferred Compensation Obligation Shares							(845)
Deferred Compensation Obligation							$ (16)					(16)
Issuance of LP Units							$ 8,272					8,272
Issuance of LP Units Shares							679,285
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(377)									(32)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	6						$ 6					6
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures							463
Stock Issued During Period, Value, Conversion of Units	0						$ 86,038			(86,038)		86,038
Stock Issued During Period, Shares, Conversion of Units							7,204,104
Share Choice Plan Issuance Value	(55)						$ (55)					(55)
Share Choice Plan Issuance Shares							1,684
Stock Issued During Period, Value, Restricted Stock Award, Gross	(350)						$ (352)					(352)
Stock Issued During Period, Shares, Restricted Stock Award, Gross							201,464
Restricted Stock Amortization	2,937						$ 2,937					2,937
Restricted Performance Units Amortization	1,679						1,679					1,679
Outperformance Plan Amortization	123						123					123
Amortization of ESOP Award	1,487						1,487					1,487
Trustee Fees Paid in Shares							$ 32					32
Trustee fees paid in shares units							2,672
Stock Issued During Period, Value, Stock Options Exercised	350						$ 350					350
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period							120,179
Adjustment of Redeemable Partnership Units to Liquidation Value at Period End							$ 5,778					5,778
Dividends, Preferred Stock, Cash	(7,992)						(7,992)					(7,992)
Preferred share/unit redemption charge	0	0
Partners' Capital Account, Distributions							(82,819)					(82,819)
Ending Balance at Dec. 31, 2011	1,889,696		$ 47,912	$ 43	$ 55,538	$ 0	$ 1,754,302	(6,079)	(6,426)	33,105	0	1,851,326
Ending Balance, shares at Dec. 31, 2011			2,000,000	4,300,000	2,300,000	0	142,690,755.000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	6,529	6,529					$ 6,529			(66)		6,529
Comprehensive income (loss)	(10,026)	(10,026)						(9,839)	(10,026)	(187)		(10,026)
Deferred Compensation Obligation Shares							(5,564)
Deferred Compensation Obligation							$ 0					0
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(613)						(613)					(613)
Redemption of preferred shares, Value	103,448		$ (47,912)	$ 43	$ (55,538)							(103,450)
Redemption of preferred shares, Shares			(2,000,000)	(4,300,000)	(2,300,000)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	387						$ 387					387
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures							35,703
Stock Issued During Period, Value, Conversion of Units	(167)						$ (49)			(268)		(49)
Stock Issued During Period, Shares, Conversion of Units							20,464
Partners' Capital Account, Redemptions	9,741						$ (9,741)			5,556		(9,741)
Stock Issued During Period, Value, Restricted Stock Award, Gross	(1,385)						$ (1,385)					(1,385)
Stock Issued During Period, Shares, Restricted Stock Award, Gross							293,614
Restricted Stock Amortization	3,271						$ 3,271					3,271
Restricted Stock Award, Forfeitures	(35)						35					35
Stock Issued During Period, Value, Vesting of restricted performance units	(1,495)						$ (1,495)					(1,495)
Stock Issued During Period, Shares, Vesting of restricted performance units							272,131
Restricted Performance Units Amortization	3,379						$ 3,379					3,379
Amortization of ESOP Award	1,636						1,636					1,636
Trustee Fees Paid in Shares							$ 15					15
Trustee fees paid in shares units							1,336
Stock Issued During Period, Value, Stock Options Exercised	976						$ 976					976
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period							230,294
Adjustment of Redeemable Partnership Units to Liquidation Value at Period End							$ 9,968					9,968
Dividends, Preferred Stock, Cash	(10,405)						(10,405)					(10,405)
Preferred share/unit redemption charge	(4,052)	(4,052)					(4,052)					(4,052)
Partners' Capital Account, Distributions							(86,417)					(86,417)
Ending Balance at Dec. 31, 2012	1,773,516	1,746,739	$ 0	$ 40	$ 0	$ 96,850	$ 1,666,341	(15,918)	(16,452)	21,238	0	1,746,739
Ending Balance, shares at Dec. 31, 2012			0	4,000,000	0	4,000,000	143,538,733
Preferred Stock, Value, Issued	$ 40	$ 96,850				$ 96,850						96,850
Preferred Stock, Shares Issued	4,000,000	4,000,000				4,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 43,189	$ 43,189					$ 43,189			412		43,189
Comprehensive income (loss)	13,075	13,075						12,923	13,075	152		13,075
Deferred Compensation Obligation Shares							(5,012)
Deferred Compensation Obligation							$ 0					0
Issuance of LP Units							$ 181,289					181,289
Issuance of LP Units Shares							12,650,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(744)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	946									946	(946)	(946)
Redemption of preferred shares, Value												361
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	361						$ 361					(902)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures							27,918
Stock Issued During Period, Value, Conversion of Units	0						$ 1,240			(1,240)		1,240
Stock Issued During Period, Shares, Conversion of Units							81,998
Partners' Capital Account, Redemptions							$ 17					17
Share Choice Plan Issuance Value							$ (160)					(160)
Share Choice Plan Issuance Shares							53,134
Stock Issued During Period, Value, Restricted Stock Award, Gross	(902)
Restricted Stock Amortization	3,079						$ 3,079					3,079
Stock Issued During Period, Value, Vesting of restricted performance units	(159)						$ (902)
Stock Issued During Period, Shares, Vesting of restricted performance units							147,495
Restricted Performance Units Amortization	4,333						$ 4,333					4,333
Amortization of ESOP Award	670						670					670
Trustee Fees Paid in Shares							$ 20					20
Trustee fees paid in shares units							1,409
Stock Issued During Period, Value, Stock Options Exercised	$ 2,380						$ 2,380					2,380
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	236,318						236,318
Adjustment of Redeemable Partnership Units to Liquidation Value at Period End							$ (778)					(778)
Adjustments to Additional Paid in Capital, Increase in Carrying Amount of Redeemable Preferred Stock							(1,240)					(1,240)
Dividends, Preferred Stock, Cash	$ (6,900)						(6,900)					6,900
Preferred share/unit redemption charge	0	0
Partners' Capital Account, Distributions							(92,409)					92,409
Ending Balance at Dec. 31, 2013	1,921,435	1,894,949	$ 0	$ 40	$ 0	$ 96,850	$ 1,800,530	$ (2,995)	$ (3,377)	$ 21,215	$ 946	$ 1,894,949
Ending Balance, shares at Dec. 31, 2013			0	4,000,000	0	4,000,000	156,731,993
Preferred Stock, Value, Issued	$ 40	$ 96,850
Preferred Stock, Shares Issued	4,000,000	4,000,000

Organization of The Parent Company and The Operating Partnership	12 Months Ended
	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP	ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP The Parent Company is a self-administered and self-managed real estate investment trust (“REIT”) that provides leasing, property management, development, redevelopment, acquisition and other tenant-related services for a portfolio of office and industrial properties. The Parent Company owns its assets and conducts its operations through the Operating Partnership and subsidiaries of the Operating Partnership. The Parent Company is the sole general partner of the Operating Partnership and, as of December 31, 2013, owned a 98.8% interest in the Operating Partnership. The Parent Company’s common shares of beneficial interest are publicly traded on the New York Stock Exchange under the ticker symbol “BDN”. As of December 31, 2013, the Company owned 204 properties, consisting of 176 office properties, 19 industrial facilities, five mixed-use properties, one development property, two redevelopment properties and one re-entitlement property (collectively, the “Properties”) containing an aggregate of approximately 24.8 million net rentable square feet. In addition, as of December 31, 2013, the Company owned economic interests in 17 unconsolidated real estate ventures that contain approximately 5.7 million net rentable square feet (collectively, the “Real Estate Ventures”). As of December 31, 2013, the Company also owned 432 acres of undeveloped land, and held options to purchase approximately 51 additional acres of undeveloped land. As of December 31, 2013, the total potential development that these land parcels could support, under current zoning, entitlements or combination thereof, amounted to 6.8 million square feet. The Properties and the properties owned by the Real Estate Ventures are located in or near Philadelphia, Pennsylvania; Metropolitan Washington, D.C.; Southern New Jersey; Richmond, Virginia; Wilmington, Delaware; Austin, Texas and Oakland, Concord and Carlsbad, California. In addition to managing properties that the Company owns, as of December 31, 2013, the Company was managing approximately 7.9 million net rentable square feet of office and industrial properties for third parties and the Real Estate Ventures. All references to building square footage, acres, occupancy percentage and the number of buildings are unaudited. The Company conducts its third-party real estate management services business primarily through six management companies (collectively, the “Management Companies”): Brandywine Realty Services Corporation (“BRSCO”), BTRS, Inc. (“BTRS”), Brandywine Properties I Limited, Inc. (“BPI”), BDN Brokerage, LLC (“BBL”), Brandywine Properties Management, L.P. (“BPM”) and Brandywine Brokerage Services, LLC (“BBS”). Each of BRSCO, BTRS and BPI is a taxable REIT subsidiary. As of December 31, 2013, the Operating Partnership owns, directly and indirectly, 100% of each of BRSCO, BTRS, BPI, BBL, BPM and BBS. As of December 31, 2013, the Management Companies were managing properties containing an aggregate of approximately 32.7 million net rentable square feet, of which approximately 24.8 million net rentable square feet related to Properties owned by the Company and approximately 7.9 million net rentable square feet related to properties owned by third parties and Real Estate Ventures.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Reclassifications

Certain amounts have been reclassified in prior years to conform to the current year presentation. The reclassifications are related to the treatment of sold properties as discontinued operations on the statement of operations for all periods presented. In addition, capital expenditures included in investing activities were disaggregated on the statement of cash flows for all periods presented to the following; (i) capital expenditures for tenant improvements, (ii) capital expenditures for redevelopment projects and (iii) capital expenditures for development projects.

Principles of Consolidation

When the Company obtains an economic interest in an entity, the Company evaluates the entity to determine if the entity is deemed a variable interest entity (“VIE”), and if the Company is deemed to be the primary beneficiary, in accordance with the accounting standard for the consolidation of variable interest entities. The accounting standard for the consolidation of VIEs requires the Company to qualitatively assess if the Company was the primary beneficiary of the VIEs based on whether the Company had (i) the power to direct those matters that most significantly impacted the activities of the VIE and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. For entities determined to be VIEs, but for which the Company is not the primary beneficiary, the Company's maximum exposure to loss is the carrying amount of its investments. As of December 31, 2013, the Company has provided guarantees on behalf of certain real estate ventures, consisting of (i) a $24.7 million payment guaranty on the construction loan for the project being undertaken by evo at Cira; (ii) a $3.2 million payment guarantee on the construction loan for a project being undertaken by TB-BDN Plymouth Apartments; and (iii) a $0.5 million payment guarantee on a loan provided to PJP VII.

When an entity is not deemed to be a VIE, the Company considers the provisions of the same accounting standard to determine whether a general partner/managing member, or the general partners/managing members as a group, controls a limited partnership or similar entity when the limited partners/non-managing members have certain rights. The Company consolidates (i) entities that are VIEs and of which the Company is deemed to be the primary beneficiary and (ii) entities that are non-VIEs and controlled by the Company and in which the limited partners neither have the ability to dissolve the entity or remove the Company without cause nor any substantive participating rights. Entities that the Company accounts for under the equity method (i.e., at cost, increased or decreased by the Company's share of earnings or losses, plus contributions, less distributions) include (i) entities that are VIEs and of which the Company is not deemed to be the primary beneficiary (ii) entities that are non-VIEs which the Company does not control, but over which the Company has the ability to exercise significant influence and (iii) entities that are non-VIEs for which the Company maintains an ownership interest through its general partner/managing member status, but the limited partners/non-managing members in the entity have the substantive ability to dissolve the entity or remove the Company without cause or have substantive participating rights. Currently there are no real estate ventures that a limited partner/non-managing member has the unilateral right to dissolve. The Company continuously assesses its determination of whether an entity is a VIE and who the primary beneficiary is, and whether or not the limited partners/non-managing members in an entity have substantive rights, more particularly if certain events occur that are likely to cause a change in the original determinations. The Company's assessment includes a review of applicable documents such as, but not limited to, applicable partnership agreements, LLC and other real estate venture agreements and management and leasing agreements to determine whether the Company has control to direct the business activities of the entities. The portion of the consolidated entities that is not owned by the Company is presented as non-controlling interest as of and during the periods consolidated. All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Management makes significant estimates regarding revenue, valuation of real estate and related intangible assets and liabilities, impairment of long-lived assets, allowance for doubtful accounts and deferred costs.

Operating Properties

Operating properties are carried at historical cost less accumulated depreciation and impairment losses. The cost of operating properties reflects their purchase price or development cost. Acquisition costs related to business combinations are expensed as incurred, whereas the costs related to asset acquisitions are capitalized as incurred. Costs incurred for the renovation and betterment of an operating property are capitalized to the Company’s investment in that property. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. Fully-depreciated assets are removed from the accounts.

Purchase Price Allocation

The Company allocates the purchase price of properties considered to be business combinations to net tangible and identified intangible assets acquired based on fair values. Above-market and below-market in-place lease values for acquired properties are recorded based on the present value (using an interest rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place leases and (ii) the Company’s estimate of the fair market lease rates for the corresponding in-place leases, measured over a period equal to the remaining non-cancelable term of the lease (including the below market fixed renewal period, if applicable). Capitalized above-market lease values are amortized as a reduction of rental income over the remaining non-cancelable terms of the respective leases. Capitalized below-market lease values are amortized as an increase to rental income over the remaining non-cancelable terms of the respective leases, including any below market fixed-rate renewal periods.

Other intangible assets also include in-place leases based on the Company’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. The Company estimates the cost to execute leases with terms similar to the remaining lease terms of the in-place leases, including leasing commissions, legal and other related expenses. This intangible asset is amortized to expense over the remaining term of the respective leases and any fixed-rate bargain renewal periods. Company estimates of value are made using methods similar to those used by independent appraisers or by using independent appraisals. Factors considered by the Company in this analysis include an estimate of the carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, which primarily range from four to twelve months. The Company also considers information obtained about each property as a result of its pre-acquisition due diligence, marketing and leasing activities in estimating the fair value of the tangible and intangible assets acquired. The Company also uses the information obtained as a result of its pre-acquisition due diligence as part of its consideration of the accounting standard governing asset retirement obligations and when necessary, will record a conditional asset retirement obligation as part of its purchase price. Though the Company considers the value of tenant relationships, the amounts are determined on a tenant-specific basis. On certain of our acquisitions this intangible has been deemed immaterial. In these instances no related intangible value is assigned.

In the event that a tenant terminates its lease, the unamortized portion of each intangible, including in-place lease values and tenant relationship values, is charged to expense and market rate adjustments (above or below) are recorded to revenue.

Depreciation and Amortization

The costs of buildings and improvements are depreciated using the straight-line method based on the following useful lives: buildings and improvements (five to 55 years) and tenant improvements (the shorter of the lease term or the life of the asset).

The Company's 2011 consolidated statement of operations contained an out of period depreciation and amortization expense adjustment of $4.7 million relating to intangible assets representing tenant relationships and in-place leases that should have been written off in prior periods. This resulted in the overstatement of depreciation and amortization expense by $4.7 million in 2011. During the year ended December 31, 2010, depreciation and amortization expense was overstated by $1.7 million and was understated by $1.4 million, $1.8 million, $1.7 million and $1.5 million during the years ended December 31, 2009, 2008, 2007, and 2006, respectively. As management believes that this error was not material to prior years' consolidated financial statements and that the impact of recording the error during 2011 was not material to the Company's consolidated financial statements, the Company recorded the related adjustment during 2011.

Construction in Progress

Project costs directly associated with the development and construction of a real estate project are capitalized as construction in progress. Construction in progress also includes costs related to ongoing tenant improvement projects. In addition, interest, real estate taxes and other expenses that are directly associated with the Company’s development activities are capitalized until the property is placed in service. Internal direct costs are capitalized to projects in which qualifying expenditures are being incurred. Internal direct construction costs totaling $3.7 million in 2013, $4.7 million in 2012, $4.0 million in 2011 and interest totaling $2.6 million in 2013, $2.6 million in 2012, and $2.0 million in 2011 were capitalized related to development of certain properties and land holdings.

During the years ended December 31, 2013, 2012 and 2011, the Company's internal direct construction costs are comprised entirely of capitalized salaries. The following table shows the amount of compensation costs (including bonuses and benefits) capitalized for the years presented (in thousands):



	December 31,
	2013		2012		2011
Development	$	156	$	57	$	—
Redevelopment	194		353		—
Tenant Improvements	3,323		4,259		4,034
Total	$	3,673	$	4,669	$	4,034

Impairment or Disposal of Long-Lived Assets

The Company reviews its long-lived assets for impairment following the end of each quarter and when there is an event or change in circumstances that indicates an impairment in value. An impairment loss is recognized if the carrying amount of an asset is not recoverable and exceeds its fair value. In such case, an impairment loss is recognized in the amount of the excess of the carrying amount of the asset over its fair value. The evaluation of anticipated cash flows is highly subjective and is based in part on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results in future periods. Since cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset has been impaired, our established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If our holding strategy were to change or if market conditions were to otherwise dictate an earlier sale date, then an impairment loss may be recognized and such loss could be material. If we determine that impairment has occurred, the affected assets must be reduced to their fair value.

The relevant accounting guidance for impairments requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and if we will not have significant continuing involvement following the sale. The components of the property’s net income that is reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally consider assets to be “held for sale” when the transaction has been approved by our Board of Trustees, or by officers vested with authority to approve the transaction and there are no known significant contingencies relating to the sale of the property within one year of the consideration date and the consummation of the transaction is otherwise considered probable.

Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value.

The Company determined during its impairment review of the year-ended December 31, 2013, 2012 and 2011, that no impairment charges were necessary.

Cash and Cash Equivalents

Cash and cash equivalents are highly-liquid investments with original maturities of three months or less. The Company maintains cash equivalents in financial institutions in excess of insured limits, but believes this risk is mitigated by only investing in or through major financial institutions.

Restricted Cash

Restricted cash consists of cash held as collateral to provide credit enhancement for the Company’s mortgage debt, cash for property taxes, capital expenditures and tenant improvements.

Accounts Receivable and Accrued Rent Receivable

Leases with tenants are accounted for as operating leases. Minimum annual rentals under tenant leases are recognized on a straight-line basis over the term of the related lease. The cumulative difference between lease revenue recognized under the straight-line method and contractual lease payment terms is recorded as “accrued rent receivable, net” on the accompanying balance sheets. Included in current tenant receivables are tenant reimbursements which are comprised of amounts recoverable from tenants for common area maintenance expenses and certain other recoverable expenses that are recognized as revenue in the period in which the related expenses are incurred. As of December 31, 2013 and 2012, no tenant represented more than 10% of accounts receivable and accrued rent receivable.

Tenant receivables and accrued rent receivables are carried net of the allowances for doubtful accounts of $3.2 million and $13.0 million in 2013, respectively and $3.1 million and $13.5 million in 2012, respectively. The allowance is an estimate based on two calculations that are combined to determine the total amount reserved. First, the Company evaluates specific accounts where it has determined that a tenant may have an inability to meet its financial obligations. In these situations, the Company uses its judgment, based on the facts and circumstances, and records a specific reserve for that tenant against amounts due to reduce the receivable to the amount that the Company expects to collect. These reserves are reevaluated and adjusted as additional information becomes available. Second, a reserve is established for all tenants based on a range of percentages applied to receivable aging categories for tenant receivables. For accrued rent receivables, the Company considers the results of the evaluation of specific accounts and also considers other factors including assigning risk factors to different industries based on its tenants SIC classification. Considering various factors including assigning a risk factor to different industries, these percentages are based on historical collection and write-off experience adjusted for current market conditions, which requires management’s judgments.

Investments in Unconsolidated Real Estate Ventures

The Company accounts for its investments in unconsolidated Real Estate Ventures under the equity method of accounting as it is not the primary beneficiary (for VIEs) and the Company exercises significant influence, but does not control these entities under the provisions of the entities’ governing agreements pursuant to the accounting standard for the consolidation of VIEs. When the Company determines that its investment in an unconsolidated Real Estate Venture does not constitute a VIE, the Company utilizes the voting interest model under the accounting standard for consolidation to determine whether to consolidate the venture.

Under the equity method, investments in unconsolidated Real Estate Ventures are recorded initially at cost, as investments in Real Estate Ventures, and subsequently adjusted for equity in earnings, cash contributions, less distributions and impairments. On a periodic basis, management also assesses whether there are any indicators that the value of the Company’s investments in unconsolidated Real Estate Ventures may be other than temporarily impaired. An investment is impaired only if the value of the investment, as estimated by management, is less than the carrying value of the investment and the decline is other than temporary. To the extent that an impairment has occurred, the loss shall be measured as the excess of the carrying amount of the investment over the fair value of the investment, as estimated by management. The determination as to whether an impairment exists requires significant management judgment about the fair value of its ownership interest. Fair value is determined through various valuation techniques, including but not limited to, discounted cash flow models, quoted market values and third party appraisals.

When the Company acquires an interest in or contributes assets to a real estate venture project, the difference between the Company’s cost basis in the investment and the value of the real estate venture or asset contributed is amortized over the life of the related assets, intangibles and liabilities and such adjustment is included in the Company’s share of equity in income of unconsolidated Real Estate Ventures. For purposes of cash flow presentation, distributions from unconsolidated Real Estate Ventures are presented as part of operating activities when they are considered as return on investments. Distributions in excess of the Company’s share in the cumulative unconsolidated Real Estate Ventures’ earnings are considered as return of investments and are presented as part of investing activities in accordance with the accounting standard for cash flow presentation.

Deferred Costs

Costs incurred in connection with property leasing are capitalized as deferred leasing costs. Deferred leasing costs consist primarily of leasing commissions and internal leasing costs that are amortized using the straight-line method over the life of the respective lease which generally ranges from one to 15 years. Management re-evaluates the remaining useful lives of leasing costs as economic and market conditions change.

Costs incurred in connection with debt financing are capitalized as deferred financing costs and charged to interest expense over the terms of the related debt agreements. Deferred financing costs consist primarily of loan fees which are amortized over the related loan term on a basis that approximates the effective interest method. Deferred financing costs are accelerated, when debt is extinguished, as part of interest expense- amortization of deferred financing costs within the Company's consolidated statements of operations. Original issue discounts are recognized as part of the gain or loss on extinguishment of debt, as appropriate.

Notes Receivable

As of December 31, 2013 and 2012, notes receivable included a purchase money mortgage with a 20-year amortization period bearing interest at 8.5%, which was valued at $7.0 million and $7.2 million, respectively. The borrower had previously defaulted on the note. As a result, a forbearance agreement dated October 2011, as amended by a second forbearance agreement dated July 9, 2013, was entered into between the Company and the borrower, outlining the repayment terms of the outstanding debt. The Company has determined that the loan modifications represent a troubled debt restructuring due to the fact that the borrower was considered to be in a financial difficulty when it defaulted on the mortgage debt, and that a concession was granted in the form of the forbearance agreements. In accordance with the accounting standard for loan receivables the Company performs, on an ongoing basis, a collectability assessment of the note using the expected cash flow information provided by the borrower. Based on settlements subsequent to the balance sheet date and future cash flow projections provided by the borrower, it is anticipated that the note will be fully paid during 2015. As of December 31, 2013, the present value of the expected cash flows of the note receivable exceeded the outstanding balance of the note and therefore the note is considered recoverable as of December 31, 2013.

During 2012, the $23.5 million seven year purchase money mortgage note receivable (balance as of the payment date, including accrued but unpaid interest), which related to the 2009 sale of two Trenton properties, was paid in full prior to its scheduled maturity of October 2016. The Company also recognized a $12.9 million deferred gain and $1.0 million of interest income at the time of payment, in accordance with the accounting standard for installment sales.

Revenue Recognition

Rental revenue is recognized on the straight-line basis, which averages minimum rents over the terms of the leases from the later of the date of the commencement of the lease or the date of acquisition of the property subject to existing leases. The straight-line rent adjustment increased revenue by approximately $17.7 million in 2013, $21.1 million in 2012 and $17.9 million in 2011. Deferred rents on the balance sheet represent rental revenue received prior to their due dates and amounts paid by the tenant for certain improvements considered to be landlord assets that will remain as the Company’s property at the end of the tenant’s lease term. The amortization of the amounts paid by the tenant for such improvements is calculated on a straight-line basis over the term of the tenant’s lease and is a component of straight-line rental income and increased revenue by $2.4 million in each of 2013, 2012 and 2011. Lease incentives, which are included as reductions of rental revenue in the accompanying consolidated statements of operations, are recognized on a straight-line basis over the term of the lease. Lease incentives decreased revenue by $0.7 million in 2013, $0.8 million in 2012, and $1.6 million in 2011.

The Company's leases also typically provide for tenant reimbursement of a portion of common area maintenance expenses and other operating expenses to the extent that a tenant’s pro rata share of expenses exceeds a base year level set in the lease or to the extent that the tenant has a lease on a triple net basis. For certain leases, the Company makes significant assumptions and judgments in determining the lease term, including assumptions when the lease provides the tenant with an early termination option. The lease term impacts the period over which the Company determines and records minimum rents and also impacts the period over which the Company amortizes lease-related costs.

In addition, the Company's rental revenue is impacted by the Company's determination of whether improvements to the properties, whether made by the Company or by the tenant, are landlord assets. The determination of whether an improvement is a landlord asset requires judgment. In making this judgment, our primary consideration is whether the improvement would be utilizable by another tenant upon move out of the improved space by the then-existing tenant. If the Company has funded an improvement that it determines not to be landlord assets, then it treats the costs of the improvement as lease incentives. If the tenant has funded the improvement that the Company determines to be landlord assets, then the Company treats the costs of the improvement as deferred revenue and amortize this cost into revenue over the lease term.

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance expenses, real estate taxes and other recoverable costs are recognized as revenue in the period during which the expenses are incurred.

Tenant reimbursements are recognized and presented in accordance with accounting guidance which requires that these reimbursements be recorded on a gross basis because the Company is generally the primary obligor with respect to the goods and services the purchase of which gives rise to the reimbursement obligation; because the Company has discretion in selecting the vendors and suppliers; and because the Company bears the credit risk in the event they do not reimburse the Company. The Company also receives payments from third parties for reimbursement of a portion of the payroll and payroll-related costs for certain of the Company's personnel allocated to perform services for these third parties and reflects these payments on a gross basis.

The Company recognizes gains on sales of real estate at times and in amounts determined in accordance with the accounting guidance for sales of real estate. The guidance takes into account the terms of the transaction and any continuing involvement, including in the form of management, leasing of space or financial assistance associated with the properties. If the sales criteria for the full accrual method are not met, then the Company defers some or all of the gain recognition and account for the continued operations of the property by applying the finance, leasing, profit sharing, deposit, installment or cost recovery method, as appropriate, until the sales criteria are met

The Company derives parking revenues from leases, monthly parking and transient parking. The Company recognizes parking revenue as earned.

The Company receives management and development fees from third parties.

Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents. The Company records development fees as earned taking into account the risk associated with each project. Profit on development fees earned from joint venture projects is recognized as revenue to the extent of the third party partners’ ownership interest.

No tenant represented greater than 10% of the Company’s rental revenue in 2013, 2012 or 2011.

Income Taxes

Parent Company

The Parent Company has elected to be treated as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “Code”). In order to continue to qualify as a REIT, the Parent Company is required to, among other things, distribute at least 90% of its annual REIT taxable income to its shareholders and meet certain tests regarding the nature of its income and assets. As a REIT, the Parent Company is not subject to federal and state income taxes with respect to the portion of its income that meets certain criteria and is distributed annually to its shareholders. Accordingly, no provision for federal and state income taxes is included in the accompanying consolidated financial statements with respect to the operations of the Parent Company. The Parent Company intends to continue to operate in a manner that allows it to meet the requirements for taxation as a REIT. If the Parent Company fails to qualify as a REIT in any taxable year, it will be subject to federal and state income taxes and may not be able to qualify as a REIT for the four subsequent tax years. The Parent Company is subject to certain local income taxes. Provision for such taxes has been included in general and administrative expenses in the Parent Company’s Consolidated Statements of Operations and Comprehensive Income.

The tax basis of the Parent Company’s assets was $4.0 billion for each of the years ended December 31, 2013 and 2012.

The Parent Company is subject to a 4% federal excise tax if sufficient taxable income is not distributed within prescribed time limits. The excise tax equals 4% of the annual amount, if any, by which the sum of (a) 85% of the Parent Company’s ordinary income and (b) 95% of the Parent Company’s net capital gain exceeds cash distributions and certain taxes paid by the Parent Company. No excise tax was incurred in 2013, 2012, or 2011.

The Parent Company has elected to treat several of its subsidiaries as taxable REIT subsidiaries (each a “TRS”). A TRS is subject to federal, state and local income tax. In general, a TRS may perform non-customary services for tenants, hold assets that the Parent Company, as a REIT, cannot hold directly and generally may engage in any real estate or non-real estate related business. The Company’s taxable REIT subsidiaries did not have any tax provisions or deferred income tax items as of December 31, 2013 and 2012.

Operating Partnership

In general, the Operating Partnership is not subject to federal and state income taxes, and accordingly, no provision for income taxes has been made in the accompanying consolidated financial statements. The partners of the Operating Partnership are required to include their respective share of the Operating Partnership’s profits or losses in their respective tax returns. The Operating Partnership’s tax returns and the amount of allocable Partnership profits and losses are subject to examination by federal and state taxing authorities. If such examination results in changes to the Operating Partnership profits or losses, then the tax liability of the partners would be changed accordingly.

The tax basis of the Operating Partnership’s assets was $4.0 billion for each of the years ended December 31, 2013 and 2012.

The Operating Partnership may elect to treat one or more of its subsidiaries as REITs under Sections 856 through 860 of the Code. Each subsidiary REIT has met the requirements for treatment as a REIT under Sections 856 through 860 of the Code, and, accordingly, no provision has been made for federal and state income taxes in the accompanying consolidated financial statements. If any subsidiary REIT fails to qualify as a REIT in any taxable year, that subsidiary REIT will be subject to federal and state income taxes and may not be able to qualify as a REIT for the four subsequent taxable years. Also, each subsidiary REIT may be subject to certain local income taxes.

The Operating Partnership has elected to treat several of its subsidiaries as TRSs, which are subject to federal, state and local income tax.

Earnings Per Share

Basic earnings per share ("EPS") is computed by dividing net income available to common shareholders, as adjusted for unallocated earnings, if any, of certain securities, by the weighted average number of shares of common stock outstanding during the year. Diluted EPS reflects the potential dilution that could occur from shares issuable in connection with awards under share-based compensation plans, including upon the exercise of stock options, and conversion of the noncontrolling interests in the Operating Partnership.

Earnings Per Unit

Basic EPS is computed by dividing net income available to common unitholders, as adjusted for unallocated earnings, if any, of certain securities issued by the Operating Partnership, by the weighted average number of common unit equivalents outstanding during the year. Diluted EPS reflects the potential dilution that could occur from shares issuable in connection with awards under share-based compensation plans, including upon the exercise of stock options.

Stock-Based Compensation Plans

The Parent Company maintains a shareholder-approved equity-incentive plan known as the Amended and Restated 1997 Long-Term Incentive Plan (the “1997 Plan”). The 1997 Plan is administered by the Compensation Committee of the Parent Company’s Board of Trustees. Under the 1997 Plan, the Compensation Committee is authorized to award equity and equity-based awards, including incentive stock options, non-qualified stock options, restricted shares and performance-based shares. On June 2, 2010, the Parent Company’s shareholders approved amendments to the 1997 Plan that, among other things, increased the number of common shares available for future awards under the 1997 Plan by 6,000,000 (of which 3,600,000 shares are available solely for options and share appreciation rights). As of December 31, 2013, 5,195,177 common shares remained available for future awards under the 1997 Plan (including 2,983,569 shares available solely for options and share appreciation rights). Through December 31, 2013 all options awarded under the 1997 Plan had a one to ten-year term.

The Company incurred stock-based compensation expense of $8.3 million during 2013, of which $1.4 million was capitalized as part of the Company’s review of employee salaries eligible for capitalization. The Company incurred stock-based compensation expense of $8.6 million and $6.4 million during 2012 and 2011, of which $2.6 million and $1.5 million, respectively, were also capitalized. The expensed amounts are included in general and administrative expense on the Company’s consolidated income statement in the respective periods.

Comprehensive Income

Comprehensive income or loss is recorded in accordance with the provisions of the accounting standard for comprehensive income. The accounting standard establishes standards for reporting comprehensive income and its components in the financial statements. Comprehensive income includes the effective portions of changes in the fair value of derivatives.

Accounting for Derivative Instruments and Hedging Activities

The Company accounts for its derivative instruments and hedging activities in accordance with the accounting standard for derivative and hedging activities. The accounting standard requires the Company to measure every derivative instrument (including certain derivative instruments embedded in other contracts) at fair value and record them in the balance sheet as either an asset or liability. See disclosures below related to the accounting standard for fair value measurements and disclosures.

For derivatives designated as cash flow hedges, the effective portions of changes in the fair value of the derivative are reported in other comprehensive income while the ineffective portions are recognized in earnings.

The Company actively manages its ratio of fixed-to-floating rate debt. To manage its fixed and floating rate debt in a cost-effective manner, the Company, from time to time, enters into interest rate swap agreements as cash flow hedges, under which it agrees to exchange various combinations of fixed and/or variable interest rates based on agreed upon notional amounts.

Fair Value Measurements

The Company estimates the fair value of its derivatives in accordance with the accounting standard for fair value measurements and disclosures. The accounting standard defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. It also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value. Financial assets and liabilities recorded on the Consolidated Balance Sheets are categorized based on the inputs to the valuation techniques as follows:


•	Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access;

•

Level 2 inputs are inputs other than quoted prices included in Level 1, that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals; and


•	Level 3 inputs are unobservable inputs for the asset or liability, which is typically based on an entity’s own assumptions, as there is little, if any, related market activity or information.

In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.

The following table sets forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis as of December 31, 2013 (in thousands):



	Fair Value Measurements at Reporting Date Using:
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Unobservable Inputs
Description	2013		(Level 1)		(Level 2)		(Level 3)
Recurring
Assets:
Interest Rate Swaps	$	767	$	—	$	767	$	—
Liabilities:
Interest Rate Swaps	$	2,188	$	—	$	2,188	$	—

The following table sets forth the Company’s financial liabilities that were accounted for at fair value on a recurring basis as of December 31, 2012 (in thousands):



	Fair Value Measurements at Reporting Date Using:
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Unobservable Inputs
Description	2012		(Level 1)		(Level 2)		(Level 3)
Recurring
Liabilities:
Interest Rate Swaps	$	14,210	$	—	$	14,210	$	—

We classify our interest rate swaps, shown above, within Level 2 as the valuation inputs are based on quoted prices and market observable data of similar instruments.

Non-financial assets and liabilities recorded at fair value on a non-recurring basis to which the Company would apply the accounting standard where a measurement was required under fair value would include:


•	Non-financial assets and liabilities initially measured at fair value in an acquisition or business combination that are not remeasured at least quarterly at fair value,


•	Long-lived assets measured at fair value due to an impairment in accordance with the accounting standard for the impairment or disposal of long-lived assets,


•	Equity and cost method investments measured at fair value due to an impairment in accordance with the accounting standard for investments,


•	Notes receivable adjusted for any impairment in its value in accordance with the accounting standard for loan receivables, and


•	Asset retirement obligations initially measured at fair value under the accounting standard for asset retirement obligations.

Other than the remeasurements of our equity method investments of Six Tower Bridge, One Commerce Square and Two Commerce Square (see Note 3), the formation of the Austin Venture (see Note 4) and the 2013 business combinations (see Note 3), there were no items that were accounted for at fair value on a non-recurring basis for the twelve months ended December 31, 2013.

Real Estate Investments

12 Months Ended

Dec. 31, 2013

Real Estate [Abstract]

REAL ESTATE INVESTMENTS

As of December 31, 2013 and 2012 the gross carrying value of the Company’s Properties was as follows (in thousands):



	2013		2012
Land	$	680,513	$	662,107
Building and improvements	3,504,060		3,576,065
Tenant improvements	484,716		487,997
	$	4,669,289	$	4,726,169

Acquisitions and Dispositions

2013

Acquisitions

One and Two Commerce Square

On December 19, 2013, the Company acquired 99% of the common interests in the One and Two Common Square partnerships ("Commerce Square"), the entities which own two 41-story Trophy-class office towers in Philadelphia, Pennsylvania, from Parkway Properties, Inc. The office towers contain 1,896,142 of net rentable square feet and were 86.7% occupied as of December 31, 2013. The Company acquired Commerce Square for an aggregate purchase price of $331.8 million and funded the acquisition via assumption of $237.1 million of existing mortgage debt and a $73.1 million cash payment from available corporate funds.

The Company previously accounted for our non-controlling interest in Commerce Square under the equity method of accounting. As a result of acquiring a 99% common interest in the partnerships we obtained control of Commerce Square and our existing investment balance was remeasured based on the fair value of the underlying properties acquired and the existing distribution provisions under the relevant partnership agreements. Accordingly, a loss on remeasurement of $1.0 million was recorded as a result of this transaction.

The Company has treated this transaction as a business combination and allocated the purchase price to the tangible and intangible assets and liabilities. As discussed in Note 2, the Company utilized a number of sources in making estimates of fair values for purposes of allocating the purchase price to tangible and intangibles assets acquired and intangible liabilities assumed. The purchase price is allocated as follows:



	December 19, 2013
Building, land and improvements	$	255,705
Intangible assets acquired	85,036
Below market lease liabilities assumed	(8,637		)
	$	332,104

Mortgage debt assumed - at fair value (1)	(238,082		)
Return of existing equity method investment	(30,424		)
Net working capital assumed	10,423
Non-controlling interest	(946		)
Total cash payment at settlement	$	73,075

(1) Principal outstanding on assumed mortgage debt at December 19, 2013 was $237.1 million.

Intangible assets acquired and intangible liabilities assumed consist of the following (in thousands):



	December 19, 2013			Weighted Average Amortization Period (in years)
Intangible assets:
In-place lease value	$	80,916		7.9
Above market tenant leases acquired	4,120			6.9
Total	$	85,036

Intangible liabilities:
Below market leases acquired	$	(8,637	)	6.5

The Commerce Square redemption agreement allows for a 60 day settlement period related to the net working capital assets related to the acquired partnership interests. As of December 31, 2013, the Company has a $2.1 million receivable balance from its former partner which is due under the terms of the redemption agreement.

In connection with the acquisition of One Commerce Square, we assumed a $125.1 million existing non-recourse first mortgage with a fixed interest rate of 5.67% and a maturity date of January 6, 2016. In accordance with generally accepted accounting principles, the mortgage was recorded at $130.2 million to reflect the fair value.

In connection with the acquisition of Two Commerce Square, we assumed a $112.0 million existing non-recourse first mortgage with a fixed interest rate of 3.96% and a maturity date of April 5, 2023. In accordance with generally accepted accounting principles, the mortgage was recorded at $107.9 million to reflect the fair value.

The Company recognized $0.9 million of acquisition related costs which are included as part of general and administrative expenses of the Company’s consolidated statement of operations.

Four Points Centre

On December 19, 2013, the Company acquired two 3-story, Class A office buildings totaling 192,396 of net rentable square feet known as Four Points Centre, together with 22.3 acres of nearby parcels of land in Austin, Texas known for an aggregate $47.3 million. This property was 99.2% occupied as of December 31, 2013. The Company funded the acquisition price with available corporate funds, while recognizing $0.1 million of acquisition related costs, which are included as part of general and administrative expenses in the Company's consolidated statements of operations. The acquisition has been treated as a business combination and the total purchase price was allocated as follows: $36.0 million to building, $5.8 million to land, $6.5 million to intangible assets and $1.0 million to below market lease liabilities assumed.

Six Tower Bridge

On June 19, 2013, the Company acquired the remaining ownership interest in the real estate venture known as "Six Tower Bridge" that it did not then already own. See Note 4 "Investments in Unconsolidated Real Estate Ventures" for further discussion.

The unaudited pro forma information below summarizes the Company’s combined results of operations for the years ended December 31, 2013 and 2012 as though the acquisition of One and Two Commerce Square, Four Points Centre and Six Tower Bridge were completed on January 1, 2012. The supplemental pro forma operating data is not necessarily indicative of what the actual results of operations would have been assuming the transaction had been completed as set forth above, nor do they purport to represent the Company’s results of operations for future periods (in thousands except for per share amounts).



	December 31,
	2013		2012

Pro forma revenue	$	610,979	$	592,753
Pro forma income (loss) from continuing operations	21,805		(60,011		)
Pro forma net income (loss) available to common shareholders	25,957		(16,970		)

Earnings per common share from continuing operations:
Basic -- as reported	$	0.20	$	(0.36	)
Basic -- as pro forma	$	0.14	$	(0.42	)

Diluted -- as reported	$	0.20	$	(0.36	)
Diluted -- as pro forma	$	0.14	$	(0.42	)

Earnings per common share:
Basic -- as reported	$	0.23	$	(0.06	)
Basic -- as pro forma	$	0.17	$	(0.12	)

Diluted -- as reported	$	0.23	$	(0.06	)
Diluted -- as pro forma	$	0.17	$	(0.12	)

Included in the consolidated statements of income for the year ended December 31, 2013 are total revenues of $3.4 million and a net loss attributable to common shareholders of $0.2 million from acquisitions made during 2013.

Cira Centre

On November 19, 2013, the Company acquired a 0.8 acre land parcel underlying Cira Centre in Philadelphia, Pennsylvania for $24.6 million. The purchase terminates a long term ground lease agreement entered into during the development of Cira Centre. The Company has accounted for the transaction as an asset acquisition. Prior to the acquisition date, the Company recorded ground rent expense on a straight-line basis, resulting in accrued rent liability of $12.1 million. The accounting guidance for leases requires that an asset purchased which was previously subject to an operating lease cannot result in a gain, accordingly, the basis of the acquired land was reduced by the accrued rent liability and no income was recognized at acquisition. The Company funded the cost of the acquisition with available corporate funds and capitalized $1.4 million of acquisition related costs as part of the basis in the operating land.

Three Logan Square

On April 25, 2013, the Company exercised its purchase option under the long term ground lease agreement it held through its acquisition of Three Logan Square on August 5, 2010 and acquired the 1.8 acre land parcel underlying Three Logan Square in Philadelphia, Pennsylvania for $20.8 million. The Company has accounted for the transaction as an asset acquisition. A portion of the original purchase price of Three Logan Square was allocated to a below market ground lease intangible asset. As the sum of the purchase price of the land plus the $4.3 million remaining unamortized balance for the intangible asset approximates the fair value of the land as unencumbered by the ground lease, the remaining intangible asset balance was reclassified to land upon exercise of the purchase option. The Company funded the cost of the acquisition with available corporate funds and capitalized $0.1 million of acquisition related costs as part of the basis in the operating land.

Dispositions

On December 19, 2013, we sold a 50,000 net rentable square feet office property located in King of Prussia, Pennsylvania known as 875 First Avenue, for a sales price of $3.8 million resulting in a $0.1 million gain on sale after closing and other transaction related costs.

On October 17, 2013, we sold a 39,330 net rentable square feet office property located in West Chester, Pennsylvania known as 1336 Enterprise Drive, for a sales price of $2.6 million resulting in a $0.2 million gain on sale after closing and other transaction related costs.

On October 16, 2013 the Austin portfolio was contributed to a newly formed real estate venture. For additional information, see Note 4 to our consolidated financial statements.

On August 5, 2013, the Company sold an eight-acre parcel of land located in Richmond, Virginia known as Dabney Land East, for a sales price of $0.5 million resulting in a $0.1 million loss on sale after closing and other transaction related costs. The land parcel was undeveloped as of the date of sale.

On June 28, 2013, the Company sold 16870 West Bernardo Drive, a 68,708 net rentable square feet office property located in San Diego, California, for a sales price of $18.0 million resulting in a $0.9 million loss on sale after closing and other transaction related costs.

On June 28, 2013, the Company sold 100 Arrandale Boulevard, a 34,931 net rentable square feet office property located in Exton, Pennsylvania, for a sales price of $3.5 million resulting in a $0.4 million loss on sale after closing and other transaction related costs.

On June 19, 2013, the Company sold 1700 Paoli Pike, a 28,000 net rentable square feet office property located in Malvern, Pennsylvania known as 100 Applebrook, for a sales price of $2.7 million resulting in a $0.4 million loss on sale after closing and other transaction related costs.

On June 14, 2013, the Company sold Pacific View Plaza, a 51,695 net rentable square feet office property located in Carlsbad, California, for a sales price of $10.3 million resulting in a $0.5 million loss on sale after closing and other transaction related costs.

On February 25, 2013, the Company sold a portfolio of eight office properties containing 800,546 square feet in Lawrenceville, New Jersey, known as "Princeton Pike Corporate Center," for an aggregate sales price of $121.0 million resulting in a $5.3 million gain on sale after closing and other transaction related costs.

The sales of these properties, with the exception of the Austin portfolio and Dabney Land East, are included in discontinued operations (see Note 10).

2012

Brandywine/Toll Brothers Venture Formation

On September 5, 2012, the Company formed a joint venture, TB-BDN Plymouth Apartments, L.P., (the "Venture"), with Toll Brothers, Inc. ("Toll Brothers"), a residential home builder. The Company and Toll Brothers each own a 50% interest in the Venture. The Venture owns a 20-acre parcel of land located in Plymouth Meeting, Pennsylvania, which the Company contributed to the Venture upon its formation. Concurrent with the Company's contribution of the aforementioned land parcel, Toll Brothers contributed $15.5 million of cash to the venture, equivalent to the fair value of the land parcel contributed by the Company. The Venture will use the cash contributed by Toll Brothers to fund predevelopment costs for construction of a 398 unit apartment complex.

Based on the facts and circumstances at the date of formation of the Venture, and in accordance with applicable accounting standards for the consolidation of variable interest entities, or VIEs, the Company determined that the Venture is not a VIE. Accordingly, the Company used the voting interest model under the accounting standards for consolidation to determine whether to consolidate the Venture. Under the joint venture agreement for the Venture, each of the Company and Toll Brothers has significant participating rights and the Company does not have exclusive control over the development or construction phases of the Venture's project. Because each partner has significant participating rights, the Company deconsolidated the land parcel that was contributed to the Venture, and the Company is accounting for the Venture under the equity method of accounting. As of December 31, 2012, the carrying amount of the Company's equity investment in the Venture equaled $15.2 million, with an associated $0.3 million permanent basis adjustment accounting for the difference between the fair value and carrying amount of the land parcel contributed by the Company. This basis adjustment will remain unamortized until the property is sold to a third party or until the Venture is dissolved, in accordance with the accounting standard for equity method investment.

Brandywine AI Venture - Station Square Acquisition

On July 10, 2012, the Company contributed $26.1 million to a joint venture, Brandywine AI Venture, that the Company formed in 2011 with an affiliate of Allstate Insurance. The Company's contribution funded its share of partner capital for the Venture's $120.6 million acquisition of three office properties containing 497,896 net rentable square feet in Silver Spring, Maryland.

Acquisitions

On December 31, 2012, the Company acquired a two-building office property totaling 136,075 of net rentable square feet in Austin, Texas known as 7000 West at Lantana for $32.1 million. The Company funded the acquisition price with available corporate funds, while recognizing $0.1 million of acquisition related costs, which are included as part of general and administrative expenses in the Company's consolidated statements of operations. The acquisition was treated as a business combination and the total purchase price was allocated as follows: $20.9 million to building, $4.7 million to land, $8.4 million to intangible assets and $1.9 million to below market lease liabilities assumed.

On December 11, 2012, the Company acquired an office property containing 456,922 net rentable square feet in Philadelphia, Pennsylvania known as 1900 Market Street for $34.8 million. The Company funded the acquisition price with available corporate funds, while recognizing $0.1 million of acquisition related costs, which are included as part of general and administrative expenses in the Company's consolidated statements of operations. The acquisition was treated as a business combination and the total purchase price was allocated as follows: $17.3 million to building, $7.8 million to land, $13.5 million to intangible assets and $3.8 million to below market lease liabilities assumed.

On November 20, 2012, the Company acquired a ten-acre parcel of land in Herndon, Virginia for $2.1 million. The Company funded the acquisition price with available corporate funds. The Company accounted for this transaction as an asset acquisition and capitalized a nominal amount of acquisition related and other costs as part of land inventory on its consolidated balance sheet.

On January 6, 2012, the Company acquired a vacant office property containing 154,392 net rentable square feet in Plymouth Meeting, Pennsylvania known as 660 West Germantown Pike for $9.1 million. The Company is currently redeveloping this property. The Company funded the acquisition price with available corporate funds. The Company recognized $0.1 million of acquisition related costs that have been capitalized on our consolidated balance sheet.

Dispositions

On July 18, 2012, the Company sold a portfolio of 11 flex/office properties, totaling 466,719 square feet, in Exton, Pennsylvania, collectively known as "Oaklands Corporate Center," for a sales price of $52.7 million resulting in a $9.9 million gain on sale after closing and other transaction related costs.

On June 22, 2012, the Company sold Pacific Ridge Corporate Center, a 121,381 net rentable square feet, two-building office property located in Carlsbad, California, for a sales price of $29.0 million resulting in a $2.8 million loss on sale after closing and other transaction related costs.

On March 22, 2012, the Company sold South Lake at Dulles Corner, a 268,240 net rentable square feet office property located in Herndon, Virginia, for a sales price of $91.1 million resulting in a $14.5 million gain on sale after closing and other transaction related costs.

On January 17, 2012, the Company sold 304 Harper Drive, a 32,978 net rentable square feet office property located in Moorestown, New Jersey, for a sales price of $3.0 million resulting in a $0.2 million gain on sale after closing and other transaction related costs.

Each of these sales is included in discontinued operations (see Note 10).

Investment in Unconsolidated Ventures

12 Months Ended

Dec. 31, 2013

Equity Method Investments and Joint Ventures [Abstract]

INVESTMENT IN UNCONSOLIDATED VENTURES

As of December 31, 2013, the Company had an aggregate investment of approximately $180.5 million in 17 unconsolidated Real Estate Ventures. The Company formed or acquired interests in these ventures with unaffiliated third parties to develop or manage office properties or to acquire land in anticipation of possible development of office or residential properties. As of December 31, 2013, 11 of the real estate ventures owned 55 office buildings that contain an aggregate of approximately 5.7 million net rentable square feet; two real estate ventures owned 3.8 acres of undeveloped parcels of land; three real estate ventures owned 22.5 acres of land under active development and one real estate venture developed a hotel property that contains 137 rooms in Conshohocken, PA.

The Company accounts for its unconsolidated interests in its Real Estate Ventures using the equity method. The Company’s unconsolidated interests range from 20% to 65%, subject to specified priority allocations of distributable cash in certain of the Real Estate Ventures.

The amounts reflected in the following tables (except for the Company’s share of equity and income) are based on the historical financial information of the individual Real Estate Ventures. The Company does not record operating losses of the Real Estate Ventures in excess of its investment balance unless the Company is liable for the obligations of the Real Estate Venture or is otherwise committed to provide financial support to the Real Estate Venture.

The Company’s investment in Real Estate Ventures as of December 31, 2013 and the Company’s share of the Real Estate Ventures’ income (loss) for the year ended December 31, 2013 was as follows (in thousands):



	Ownership Percentage (a)		Carrying Amount			Company’s Share of 2013 Real Estate Venture Income (Loss)			Real Estate Venture Debt at 100%		Current Interest Rate		Debt Maturity
Broadmoor Austin Associates (f)	50	%	$	65,867		$	(52	)	$	56,616	7.04	%	Apr-23
Brandywine-AI Venture LLC	50	%	46,406			130			134,500		3.92	%	(b)
DRA (G&I) Austin (f)	50	%	17,262			(434		)	230,600		3.39	%	(c)
HSRE-Campus Crest IX, LLC (f)	30	%	13,761			—			966		L+2.20%		Jul-16
4040 Wilson LLC	50	%	13,499			—			—		N/A		N/A
TB-BDN Plymouth Apartments	50	%	12,402			5			—		L+1.70%		Dec-17
Brandywine 1919 Ventures	50	%	6,214			—			—		N/A		N/A
1000 Chesterbrook Blvd.	50	%	2,064			461			24,861		4.75	%	Dec-21
Four Tower Bridge	65	%	1,617			320			10,535		5.20	%	Feb-21
PJP VII	25	%	783			239			6,250		L+2.65%		Dec-19
Residence Inn Tower Bridge	50	%	742			326			13,700		5.63	%	Feb-16
Seven Tower Bridge	20	%	447			—			11,035		4.22	%	(d)
PJP II	30	%	330			(87		)	3,765		6.12	%	Nov-23
PJP V	25	%	175			158			5,437		6.47	%	Aug-19
PJP VI	25	%	112			70			8,404		6.08	%	Apr-23
BDN Beacon Venture LLC (i)	20	%	—			907			—		N/A		N/A
Six Tower Bridge (g)	63	%	—			165			—		N/A		N/A
One Commerce Square (h)	25	%	—			933			—		N/A		N/A
Two Commerce Square (h)	25	%	—			614			—		N/A		N/A
G&I Interchange Office LLC (DRA — N. PA) (e) (f)	20	%	—			(619		)	177,207		5.78	%	Jan-15
Two Tower Bridge (i)	35	%	—			265			—		N/A		N/A
Coppell Associates	50	%	(1,169		)	(78		)	15,984		5.75	%	Feb-16
Eight Tower Bridge (i)			—			3			—
Invesco, L.P. (i)			—			338			—
			$	180,512		$	3,664		$	699,860


(a)	Ownership percentage represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.


(b)	The debt for these properties is comprised of three fixed rate mortgages: (1) $40.0 million with a 4.40% fixed interest rate due January 1, 2019, (2) $28.0 million with a 4.65% fixed interest rate due January 1, 2022, and (3) $66.5 million with a 3.22% fixed interest rate due August 1, 2019, resulting in a time and dollar weighted average rate of 3.92%.


(c)	The debt for these properties is comprised of three mortgages: (1) $34.0 million with a 3.52% interest rate due November 1, 2018, (2) $56.0 million with a 3.19% interest rate due October 15, 2018, and (3) $140.6 million with a rate of 3.44% fixed interest rate due November 1, 2018, resulting in a time and dollar weighted average rate of 3.39%.

(d)

Comprised of two fixed rate mortgages totaling $8.0 million that mature on February 8, 2015 and accrue interest at a current rate of 6% (increasing by 1% annually through maturity), a $1.0 million 3% fixed rate loan with interest only through its September 1, 2025 maturity, and a $2.0 million 4% fixed rate loan with interest only through its February 7, 2016 maturity, resulting in a time and dollar weighted average rate of 4.22%.


(e)	Proceeds received by the Company from the sale of an 80% ownership stake in the properties exceeded the historical cost of those properties. No investment in the real estate venture was reflected on the balance sheet at formation.


(f)	The basis differences associated with these ventures are allocated between cost and the underlying equity in the net assets of the investee and is accounted for as if the entity were consolidated (i.e., allocated to the Company’s relative share of assets and liabilities with an adjustment to recognize equity in earnings for the appropriate depreciation/amortization).


(g)	On June 19, 2013, we acquired ownership of Six Tower Bridge. Real estate venture income reflects our previous partnership interest for the year to date period through June 18, 2013.


(h)	On December 19, 2013, we increased our ownership interest in One and Two Commerce Square. The real estate venture income reflects our previous partnership interest for the year to date period through December 18, 2013.


(i)	The ownership interest in these properties was disposed of prior to December 31, 2013. For further information on BDN Beacon LLC, see the section entitled BDN Beacon Venture below. For further information on Two Tower Bridge, see the section entitled Two and Six Tower Bridge Exchange Transaction below.

The following is a summary of the financial position of the Real Estate Ventures as of December 31, 2013 and December 31, 2012 (in thousands):



	December 31, 2013		December 31, 2012
Net property	$	965,475	$	923,536
Other assets	164,152		174,677
Other liabilities	49,442		53,645
Debt	699,860		724,780
Equity	380,325		319,788
Company’s share of equity (Company’s basis)	180,512		193,555

The following is a summary of results of operations of the Real Estate Ventures in which the Company had interests as of December 31, 2013, 2012 and 2011 (in thousands):



	Years ended December 31,
	2013		2012		2011
Revenue	$	102,919	$	164,013	$	145,867
Operating expenses	40,436		70,775		63,715
Interest expense, net	26,529		41,633		42,032
Depreciation and amortization	35,138		50,241		39,172
Net income	816		1,364		948
Company’s share of income (Company’s basis)	3,664		2,741		3,775

As of December 31, 2013, the aggregate principal payments of recourse and non-recourse debt payable to third-parties are as follows (in thousands):



2014	$	11,940
2015	191,304
2016	42,180
2017	13,937
2018	229,780
Thereafter	210,719
	$	699,860

Austin Venture

On October 16, 2013, the Company contributed a portfolio of seven office properties containing an aggregate of 1,398,826 square feet located in Austin, Texas (the "Austin Properties") to a newly-formed joint venture (the "Austin Venture") with G&I VII Austin Office LLC (“DRA”). The Austin Properties and related assets represent the Company's entire remaining property portfolio within the Austin, Texas region, with the exception of the acquisition of Four Points Centre disclosed in Note 3. DRA and the Company, based on arm's-length negotiation, agreed to an aggregate gross sales price of $330.0 million subject to an obligation on the Company's part to fund the first $5.2 million of post-closing capital expenditures, of which $0.8 million had been funded by us through December 31, 2013.

DRA owns a 50% interest in the Austin Venture and the Company owns a 50% interest in the Austin Venture, subject to the Company's right to receive up to an additional 10% of distributions.

At the closing the Austin Venture obtained third party debt financing of approximately $230.6 million secured by mortgages on the Austin Properties and used proceeds of this financing together with $49.7 million of cash contributions by DRA (less $1.9 million of closing costs and $6.9 million of closing prorations and lender holdbacks) to fund a $271.5 million distribution to the Company. The Company has agreed to fund the first $5.2 million of post-closing capital expenditures on behalf of the Austin Venture, resulting in net proceeds of $266.3 million after funding the Company's capital expenditure obligation. As part of the transaction, the Company's subsidiary management company executed an agreement with the Austin Venture to provide property management and leasing services to the Austin Venture in exchange for a market-based fee.

The Company and DRA, utilizing additional equity funding of up to $100.0 million per partner and to-be-determined third-party debt financing, intend to jointly pursue additional office opportunities in targeted Austin sub-markets and plan to co-invest in acquisitions that meet certain investment criteria.

Based upon the facts and circumstances at formation of the Austin Venture, the Company determined that the Austin Venture is not a VIE in accordance with the accounting standard for the consolidation of VIEs. As a result, the Company used the voting interest model under the accounting standard for consolidation in order to determine whether to consolidate the Austin Venture. Based upon each member's substantive participating rights over the activities of the Austin Venture under the operating and related agreements of the Austin Venture, it is not consolidated by the Company, and is accounted for under the equity method of accounting. As a result, the Company measured its equity interest at fair value based on the fair value of the Austin Properties and the distribution provisions of the real estate venture agreement. Since the Company retains a non-controlling interest in the Austin Properties and there are no other facts and circumstances that preclude the consummation of a sale, the contribution qualifies as a partial sale of real estate under the relevant guidance for sales of real estate. Accordingly, during the fourth quarter of 2013, the Company recorded a gain of approximately $25.9 million, which is reflected in "Net gain (loss) on real estate venture transactions" on the accompanying statement of operations.

The Company's continuing involvement with the properties through its interest in the Venture and its management and leasing activities represents a significant continuing involvement in the properties. Accordingly, under the accounting standard for reporting discontinued operations, the Company has determined that the gain on partial sale and the operations of the properties should not be included as part of discontinued operations in its consolidated statements of operations.

4040 Wilson Venture

On July 31, 2013, the Company formed 4040 Wilson LLC Venture ("4040 Wilson"), a joint venture between the Company and Ashton Park Associates LLC (“Ashton Park”), an unaffiliated third party. Each of the Company and Ashton Park owns a 50% interest in 4040 Wilson. 4040 Wilson expects to construct a 426,900 square foot office representing the final phase of the eight building, mixed-use, Liberty Center complex developed by the parent company of Ashton Park in the Ballston submarket of Arlington, Virginia. 4040 Wilson expects to develop the office building on a 1.3-acre land parcel contributed by Ashton Park to 4040 Wilson at an agreed upon value of $36.0 million. The total estimated project costs are $194.1 million, which the Company expects will be financed through approximately $72.0 million of partner capital contributions (consisting of land with a value of $36.0 million from Ashton Park and $36.0 million in cash from the Company, of which $13.5 million has been funded to date) and approximately $125.1 million of debt financing through a construction lender that has not yet been determined. As part of the 4040 Wilson venture, the Company has agreed to guarantee 100% of any lender mandated recourse. As of December 31, 2013, the Company had not provided any guarantees in respect of 4040 Wilson.

Based upon the facts and circumstances at formation of 4040 Wilson, the Company determined that 4040 Wilson is a VIE in accordance with the accounting standard for the consolidation of VIEs. As a result, the Company used the variable interest model under the accounting standard for consolidation in order to determine whether to consolidate 4040 Wilson. Based upon each member's shared power over the activities of 4040 Wilson under the operating and related agreements of 4040 Wilson, and the Company's lack of control over the development and construction phases of the project, 4040 Wilson is not consolidated by the Company, and is accounted for under the equity method of accounting.

Two and Six Tower Bridge Exchange Transaction

On June 19, 2013, the Company acquired, from an unaffiliated third party, the third party's ownership interest in the Six Tower Bridge real estate venture through a nonmonetary exchange for the Company's ownership interest in the Two Tower Bridge real estate venture. The Six Tower Bridge real estate venture owns an unencumbered office property in Conshohocken, PA. The Company previously accounted for its noncontrolling interest in Six Tower Bridge using the equity method. As a result of the exchange transaction, the Company obtained control of the Six Tower Bridge property and the Company's existing equity interest was remeasured at fair value based on the fair value of the underlying property and the distribution provisions of the real estate venture agreement. Accordingly, during 2013, the Company recorded a gain of approximately $7.8 million, which is reflected in "Net gain from remeasurement of investments in a real estate ventures" on the accompanying statement of operations. Following the acquisition, the Class A office property in Conshohocken, PA is wholly owned by the Company with an unencumbered fair value of $24.5 million. The Company accounted for this transaction as a business combination and allocated the fair value as follows: $14.8 million to building, $6.9 million to land, $3.3 million to intangible assets and $0.5 million to below market lease liabilities assumed.

As mentioned above, the Company exchanged its non-controlling interest in Two Tower Bridge real estate venture in a nonmonetary transaction with an unaffiliated third party for the third party's interest in the Six Tower Bridge real estate venture. The investment in Two Tower Bridge had a fair value of $3.6 million on the date of the exchange transaction based on the fair value of the venture's equity and the distribution provisions of the real estate venture agreement. Based on this fair value and the carrying value for the Company's investment of $(0.1) million, during 2013 the Company recognized a gain on exchange of interests in real estate ventures of $3.7 million, which is reflected in "Net gain (loss) on real estate venture transactions" on the accompanying statement of operations.

evo at Cira Centre South Venture (formerly the Grove Venture)

On January 25, 2013, the Company formed HSRE-Campus Crest IX Real Estate Venture ("evo at Cira"), a joint venture among the Company and two unaffiliated third parties: Campus Crest Properties, LLC ("Campus Crest") and HSRE-Campus Crest IXA, LLC ("HSRE"). evo at Cira has commenced construction of a 33-story, 850-bed student housing tower located in the University City submarket of Philadelphia, Pennsylvania. Each of the Company and Campus Crest owns a 30% interest in evo at Cira and HSRE owns a 40% interest. evo at Cira is developing the project on a one-acre land parcel held under a long-term ground lease with a third party lessor. The Company contributed to evo at Cira its tenancy rights under a long-term ground lease, together with associated development rights, at an agreed-upon value of $8.5 million. The total estimated project costs are $158.5 million, which will be financed through partner capital contributions totaling $60.7 million, with the remaining $97.8 million being financed through construction facilities provided by PNC Bank, Capital One and First Niagara Bank. As of December 31, 2013, we have funded 100% of our share of the equity contributions. Construction has already commenced, with a targeted project completion in 2014.

In connection with the development of evo at Cira, each of the Company and Campus Crest provided, in addition to customary non-recourse carve-out guarantees, a completion and cost overrun guaranty, as well as a payment guaranty, on the construction financing (with the Company's share of the payment guaranty being approximately $24.7 million).

The Company's historical cost basis in the development rights that it contributed to the evo at Cira was $4.0 million, thus creating a $4.5 million basis difference at December 31, 2013 between the Company's initial outside investment basis and its $8.5 million initial equity basis. As this basis difference is not related to a physical land parcel, but rather to development rights to construct evo at Cira, the Company will accrete the basis difference as a reduction of depreciation expense over the life of evo at Cira's assets.

Based upon the facts and circumstances at evo at Cira formation, the Company determined that evo at Cira is a VIE in accordance with the accounting standard for the consolidation of VIEs. As a result, the Company used the variable interest model under the accounting standard for consolidation in order to determine whether to consolidate the evo at Cira. Based upon each member's shared power over the activities of evo at Cira under the operating and related agreements of evo at Cira, and the Company's lack of exclusive control over the development and construction phases of the project, evo at Cira is not consolidated by the Company, and is accounted for under the equity method of accounting. Accordingly, the land parcel and associated development rights contributed by the Company to evo at Cira were deconsolidated by the Company upon formation of evo at Cira.

BDN Beacon Venture

On March 26, 2013, the Company sold its entire 20% ownership interest in an unconsolidated real estate venture known as BDN Beacon Venture LLC (the "Beacon Venture"). The carrying amount of the Company's investment in the Beacon Venture amounted to $17.0 million at the sale date, with the Company's proceeds effectively matching the carrying amount.

Guarantees

As of December 31, 2013, the Company has provided guarantees on behalf of certain real estate ventures, consisting of (i) a $24.7 million payment guaranty on the construction loan for the project being undertaken by evo at Cira; (ii) a $3.2 million payment guarantee on the construction loan for a project being undertaken by TB-BDN Plymouth Apartments; and (iii) a $0.5 million payment guarantee on a loan provided to PJP VII. In addition, during construction undertaken by real estate ventures the Company provided and expects to continue to provide cost overrun and completion guarantees, with rights of contribution among partners in the venture, as well as customary environmental indemnities and guarantees of customary exceptions to nonrecourse provisions in loan agreements.

Deferred Costs

12 Months Ended

Dec. 31, 2013

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Deferred Costs [Text Block]

5. DEFERRED COSTS

As of December 31, 2013 and 2012, the Company’s deferred costs were comprised of the following (in thousands):



	December 31, 2013
	Total Cost		Accumulated Amortization			Deferred Costs, net
Leasing Costs	$	155,885	$	(58,805	)	$	97,080
Financing Costs	40,317		(14,443		)	25,874
Total	$	196,202	$	(73,248	)	$	122,954



	December 31, 2012
	Total Cost		Accumulated Amortization			Deferred Costs, net
Leasing Costs	$	150,331	$	(58,343	)	$	91,988
Financing Costs	40,246		(9,991		)	30,255
Total	$	190,577	$	(68,334	)	$	122,243

During the years ended December 31, 2013, 2012 and 2011, the Company capitalized internal direct leasing costs of $7.5 million, $7.5 million, and $6.6 million, respectively, in accordance with the accounting standard for the capitalization of leasing costs.

Intangible Assets

12 Months Ended

Dec. 31, 2013

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS

As of December 31, 2013 and 2012, the Company’s intangible assets were comprised of the following (in thousands):



	December 31, 2013
	Total Cost		Accumulated Amortization			Intangible Assets, net
In-place lease value	$	150,782	$	(35,607	)	$	115,175
Tenant relationship value	38,692		(26,868		)	11,824
Above market leases acquired	6,673		(1,343		)	5,330
Total	$	196,147	$	(63,818	)	$	132,329
Below market leases acquired	$	81,991	$	(47,547	)	$	34,444



	December 31, 2012
	Total Cost		Accumulated Amortization			Intangible Assets, net
In-place lease value	$	87,909	$	(42,894	)	$	45,015
Tenant relationship value	56,137		(37,389		)	18,748
Above market leases acquired	8,565		(1,708		)	6,857
Total	$	152,611	$	(81,991	)	$	70,620
Below market leases acquired	$	77,083	$	(43,224	)	$	33,859

For the years ended December 31, 2013, 2012, and 2011, the Company wrote-off through the acceleration of amortization approximately $1.6 million, $1.4 million and $7.4 million, respectively, of intangible assets as a result of tenant move-outs prior to the end of the associated lease term. For the years ended December 31, 2013 and December 31, 2012, the Company accelerated amortization of a nominal amount of intangible liabilities as a result of tenant move-outs. For the year ended December 31, 2011, the Company accelerated amortization of $0.2 million of intangible liabilities as a result of tenant move-outs.

As of December 31, 2013, the Company’s annual amortization for its intangible assets/liabilities was as follows (in thousands, and assuming no early lease terminations):



	Assets		Liabilities
2014	$	27,043	$	7,614
2015	23,314		5,455
2016	18,573		3,486
2017	16,573		2,890
2018	12,161		2,353
Thereafter	34,665		12,646
Total	$	132,329	$	34,444

Debt Obligations

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

DEBT OBLIGATIONS

The following table sets forth information regarding the Company’s consolidated debt obligations outstanding at December 31, 2013 and 2012 (in thousands):



Property / Location	December 31, 2013			December 31, 2012			Effective Interest Rate			Maturity Date
MORTGAGE DEBT:

Tysons Corner	$	91,395		$	93,188		5.36	%		Aug-15
One Commerce Square	125,089			—			3.68	%	(a)	Jan-16
Two Logan Square	88,583			89,340			7.57	%		Apr-16
Fairview Eleven Tower	21,630			22,000			4.25	%	(b)	Jan-17
Two Commerce Square	112,000			—			4.51	%	(a)	Apr-23
IRS Philadelphia Campus	190,964			197,111			7.00	%		Sep-30
Cira South Garage	40,101			42,303			7.12	%		Sep-30
Principal balance outstanding	669,762			443,942
Plus: fair market value premiums (discounts), net	389			(968		)
Total mortgage indebtedness	$	670,151		$	442,974
UNSECURED DEBT:
Credit Facility	—			69,000			LIBOR + 1.50%			Feb-16
Three-Year Term Loan - Swapped to fixed	150,000			150,000			2.60	%		Feb-15
Four-Year Term Loan	100,000			100,000			LIBOR + 1.75%			Feb-16
Seven-Year Term Loan - Swapped to fixed	200,000			200,000			3.62	%		Feb-19
$250.0M 5.400% Guaranteed Notes due 2014	218,549			238,379			5.53	%		Nov-14
$250.0M 7.500% Guaranteed Notes due 2015	157,625			166,535			7.76	%		May-15
$250.0M 6.000% Guaranteed Notes due 2016	149,919			150,429			5.95	%		Apr-16
$300.0M 5.700% Guaranteed Notes due 2017	300,000			300,000			5.68	%		May-17
$325.0M 4.950% Guaranteed Notes due 2018	325,000			325,000			5.13	%		Apr-18
$250.0M 3.950% Guaranteed Notes due 2023	250,000			250,000			4.02	%		Feb-23
Indenture IA (Preferred Trust I)	27,062			27,062			2.75	%		Mar-35
Indenture IB (Preferred Trust I)	25,774			25,774			3.30	%		Apr-35
Indenture II (Preferred Trust II)	25,774			25,774			3.09	%		Jul-35
Principal balance outstanding	1,929,703			2,027,953
plus: original issue premium (discount), net	(4,473		)	(5,597		)
Total unsecured indebtedness	$	1,925,230		$	2,022,356
Total Debt Obligations	$	2,595,381		$	2,465,330


(a)	This loan was assumed upon acquisition of the related properties on December 19, 2013. The interest rate reflects the market rate at the time of acquisition.


(b)	Represents the full debt amount of a property in a consolidated joint venture for which the Company maintains a 50% interest.

During 2013, 2012, and 2011, the Company’s weighted-average effective interest rate on its mortgage notes payable was 5.73%, 6.65%, and 6.72%, respectively. As of December 31, 2013 and 2012, the net carrying value of the Company's Properties that are encumbered by mortgage indebtedness was $669.8 million and $591.3 million, respectively.

During the year-ended December 31, 2013, the Company repurchased $29.3 million of its outstanding unsecured Notes in a series of transactions that are summarized in the following table (in thousands):



Notes	Principal		Repurchase Amount		Loss on Early Extinguishment of Debt			Acceleration of Deferred Financing Amortization
2014 5.400% Notes	$	19,830	$	20,822	$	(1,020	)	$	16
2015 7.500% Notes	8,910		9,902		(1,036		)	23
2016 6.000% Notes	510		572		(63		)	1
	$	29,250	$	31,296	$	(2,119	)	$	40

The Parent Company unconditionally guarantees the unsecured debt obligations of the Operating Partnership (or is a co-borrower with the Operating Partnership) but does not by itself incur unsecured indebtedness. The Parent Company has no material assets other than its investment in the Operating Partnership.

The Company utilizes its unsecured revolving credit facility (the "Credit Facility") for general business purposes, including funding costs of acquisitions, developments and redevelopments and repayment of other debt. The scheduled maturity date of the Credit Facility in place at December 31, 2013 is February 1, 2016. The per annum variable interest rate on the outstanding balances is LIBOR plus 1.50%. The interest rate and facility fee are subject to adjustment upon a change in the Company’s unsecured debt ratings. During each of the years ended December 31, 2013 and 2012, the weighted-average interest rates associated with the Credit Facility was 0.29% and 1.02%, respectively. As of December 31, 2013, the Company did not have any outstanding borrowings on its Credit Facility, with $1.3 million in letters of credit outstanding, leaving $598.7 million of unused availability under the Credit Facility.

The Company has the option to increase the amounts available to be advanced under the Credit Facility, the $150.0 million three-year term loan, and the $100.0 million four-year term loan by an aggregate of $200.0 million, subject to customary conditions and limitations, by obtaining additional commitments from the current lenders and other financial institutions. The Company also has the option to extend the maturity dates of each of the Credit Facility, the $150.0 million three-year term loan and the $100.0 million four-year term loan by one year, subject to payment of an extension fee and other customary conditions and limitations. The Company may repay the $150.0 million three-year term and the $100.0 million four-year term loans at any time without penalty. The $200.0 million seven-year term loan is subject to a prepayment penalty of 1.00% through February 1, 2015 with no penalty thereafter.

The spread to LIBOR for LIBOR-based loans under the Credit Facility and term loans depends on the Company's unsecured senior debt credit rating. Based on the Company's current credit rating, the spread for such loans will be 150 basis points under the Credit Facility, 175 basis points under both the $150.0 million three-year term loan and $100.0 million four-year term loan and 190 basis points under the $200.0 million seven-year term loan. At the Company's option, advances under the Credit Facility and term loans may also bear interest at a per annum floating rate equal to the higher of the prime rate or the federal funds rate plus 0.50% per annum. The Credit Facility contains a competitive bid option that allows banks that are part of the lender consortium to bid to make loans to the Company at a reduced rate. The Company executed hedging transactions that fix the rate on the $200.0 million seven-year term loan at a 3.623% average rate for its full term, and the rate on the $150.0 million three-year term loan at a 2.596% average rate for periods of three to four years. All hedges commenced on February 1, 2012 and the rates are inclusive of the LIBOR spread based on our current investment grade rating. See Note 9 for details of the interest rate swaps entered into as of December 31, 2013.

The Credit Facility and term loans contain financial and operating covenants and restrictions. The Company was in compliance with all such restrictions and financial covenants as of December 31, 2013. In the event of a default related to the financing and operating covenants, the Company's dividend distributions are limited to the greater of 95% of funds from operations or the minimum amount necessary for the Company to maintain its status as a REIT.

As of December 31, 2013, the Company’s aggregate scheduled principal payments of debt obligations, excluding amortization of discounts and premiums, were as follows (in thousands):



2014	$	232,375
2015	409,654
2016	467,705
2017	330,323
2018	336,954
Thereafter	822,454
Total principal payments	2,599,465
Net unamortized premiums/(discounts)	(4,084		)
Outstanding indebtedness	$	2,595,381

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

FAIR VALUE OF FINANCIAL INSTRUMENTS

The Company determined the fair values disclosed below using available market information and discounted cash flow analyses as of December 31, 2013 and 2012, respectively. The discount rate used in calculating fair value is the sum of the current risk free rate and the risk premium on the date of measurement of the instruments or obligations. Considerable judgment is necessary to interpret market data and to develop the related estimates of fair value. Accordingly, the estimates presented are not necessarily indicative of the amounts that the Company could realize upon disposition. The use of different estimation methodologies may have a material effect on the estimated fair value amounts shown. The Company believes that the carrying amounts reflected in the consolidated balance sheets at December 31, 2013 and 2012 approximate the fair values for cash and cash equivalents, accounts receivable, other assets, accounts payable and accrued expenses.

The following are financial instruments for which the Company’s estimates of fair value differ from the carrying amounts (in thousands):



	December 31, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Mortgage notes payable	$	669,762	$	715,244	$	443,942	$	486,412
Unsecured notes payable	$	1,401,093	$	1,471,041	$	1,430,343	$	1,553,123
Variable rate debt	$	528,610	$	526,693	$	597,610	$	595,693
Notes receivable	$	7,026	$	7,759	$	7,226	$	7,783

The fair value of the Company's unsecured notes payable is categorized at a Level 2 basis (as provided by the accounting standard for Fair Value Measurements and Disclosures). This is because the Company valued these instruments using quoted market prices as of December 31, 2013 and 2012. For the fair value of the Company's unsecured notes, the Company uses a discount rate based on the indicative new issue pricing provided by lenders.

The fair value of the Company's mortgage notes payable, variable rate debt and notes receivable are all categorized at a Level 3 basis (as provided by the accounting standard for Fair Value Measurements and Disclosures). The fair value of the variable rate debt was estimated using a discounted cash flow analysis valuation on the borrowing rates currently available to the Company for loans with similar terms and maturities, as applicable. The fair value of the mortgage debt was determined by discounting the future contractual interest and principal payments by a blended market rate for loans with similar terms, maturities and loan-to-value. The fair value of the notes receivable was determined by using the expected cash flows of the notes receivable, and discounting those cash flows using the market rate of interest for mortgage notes with a comparable level of risk. These financial instruments have been categorized as Level 3 because the Company considers the rates used in the valuation techniques to be unobservable inputs.

For the Company's mortgage loans, the Company uses an estimate based on its knowledge of the mortgage market. The weighted average discount rate for the combined variable rate debt and mortgage loans used as of December 31, 2013 was 4.534%. An increase in the discount rate used in the discounted cash flow model would result in a decrease to the fair value of the Company's long-term debt. Conversely, a decrease in the discount rate used in the discounted cash flow model would result in an increase to the fair value of the Company's long-term debt.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Risk Management and Use of Financial Instruments

12 Months Ended

Dec. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

RISK MANAGEMENT AND USE OF FINANCIAL INSTRUMENTS

Risk Management

In the course of its ongoing business operations, the Company encounters economic risk. There are three main components of economic risk: interest rate risk, credit risk and market risk. The Company is subject to interest rate risk on its interest-bearing liabilities. Credit risk is primarily the risk of inability or unwillingness of tenants to make contractually required payments and of counterparties on derivatives contracts to fulfill their obligations. Market risk is the risk of declines in the value of Company properties due to changes in rental rates, interest rates, supply and demand of similar products and other market factors affecting the valuation of properties.

Risks and Uncertainties

The ongoing recovery in the global economy has been much slower than anticipated and continue to have an influence on the volume of real estate transactions in the market and created credit stresses on many businesses. If the economy again deteriorates, vacancy rates may increase through 2014 and possibly beyond as the current economic climate continues to negatively impact tenants. The current financial markets also have an adverse effect on the Company’s Real Estate Venture partners and contractual counter parties, including counter parties in derivative contracts.

The Company’s Credit Facility, term loans and the indenture governing its unsecured public debt securities (Note 7) contain restrictions, requirements and other limitations on the ability to incur indebtedness, including total debt to asset ratios, secured debt to total asset ratios, debt service coverage ratios and minimum ratios of unencumbered assets to unsecured debt which it must maintain. The ability to borrow under the Credit Facility is subject to compliance with such financial and other covenants. In the event that the Company fails to satisfy these covenants, it would be in default under the Credit Facility, the term loans and the indenture and may be required to repay such debt with capital from other sources. Under such circumstances, other sources of capital may not be available, or may be available only on unattractive terms.

Availability of borrowings under the Credit Facility is subject to a traditional material adverse effect clause. Each time the Company borrows it must represent to the lenders that there have been no events of a nature which would have a material adverse effect on the business, assets, operations, condition (financial or otherwise) or prospects of the Company taken as a whole or which could negatively affect the ability of the Company to perform its obligations under the Credit Facility. While the Company believes that there are currently no material adverse effect events, it is possible that such an event could arise which would limit the Company’s borrowings under the Credit Facility. If an event occurs which is considered to have a material adverse effect, the lenders could consider the Company in default under the terms of the Credit Facility and any borrowings under the Credit Facility would become unavailable. If the Company is unable to obtain a waiver, this would have a material adverse effect on the Company’s financial position and results of operations.

The Company was in compliance with all financial covenants as of December 31, 2013. Management continuously monitors the Company’s compliance with and anticipated compliance with the covenants. Certain of the covenants restrict management’s ability to obtain alternative sources of capital. While the Company currently believes it will remain in compliance with its covenants, in the event that the economy deteriorates in the future, the Company may not be able to remain in compliance with such covenants, in which case a default would result absent a lender waiver.

Use of Derivative Financial Instruments

The Company’s use of derivative instruments is limited to the utilization of interest rate agreements or other instruments to manage interest rate risk exposures and not for speculative purposes. The principal objective of such arrangements is to minimize the risks and/or costs associated with the Company’s operating and financial structure, as well as to hedge specific transactions. The counterparties to these arrangements are major financial institutions with which the Company and its affiliates may also have other financial relationships. The Company is potentially exposed to credit loss in the event of non-performance by these counterparties. However, because of the high credit ratings of the counterparties, the Company does not anticipate that any of the counterparties will fail to meet these obligations as they come due. The Company does not hedge credit or property value market risks through derivative financial instruments.

The Company formally assesses, both at inception of a hedge and on an on-going basis, whether each derivative is highly-effective in offsetting changes in cash flows of the hedged item. If management determines that a derivative is not highly-effective as a hedge or if a derivative ceases to be a highly-effective hedge, the Company will discontinue hedge accounting prospectively. The related ineffectiveness would be charged to the consolidated statement of operations.

The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves.

To comply with the provisions of the accounting standard for fair value measurements and disclosures, the Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.

The following table summarizes the terms and fair values of the Company's derivative financial instruments as of December 31, 2013 and 2012. The notional amounts provide an indication of the extent of the Company's involvement in these instruments at that time, but do not represent exposure to credit, interest rate or market risks (amounts presented in thousands and included in other liabilities on the Company's consolidated balance sheets).



Hedge Product	Hedge Type	Designation		Notional Amount				Strike		Trade Date	Maturity Date	Fair value
				12/31/2013		12/31/2012						12/31/2013			12/31/2012
Assets
Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.300	%	December 22, 2011	January 30, 2021	549			(1,262		)
Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.090	%	January 6, 2012	October 30, 2019	218			(1,129		)
				$	51,548	$	51,548					$	767		$	(2,391	)
Liabilities
Swap	Interest Rate	Cash Flow	(a)	$	200,000	$	200,000	3.623	%	December 6-13, 2011	February 1, 2019	$	(545	)	$	(8,859	)
Swap	Interest Rate	Cash Flow	(a)	77,000		77,000		2.703	%	December 9-13, 2011	February 1, 2016	(887		)	(1,343		)
Swap	Interest Rate	Cash Flow	(a)	50,000		50,000		2.470	%	December 13, 2011	February 1, 2015	(283		)	(458		)
Swap	Interest Rate	Cash Flow	(a)	23,000		23,000		2.513	%	December 7-12, 2011	May 1, 2015	(162		)	(245		)
Swap	Interest Rate	Cash Flow	(a)	27,062		27,062		2.750	%	December 21, 2011	September 30, 2017	(311		)	(914		)
				$	377,062	$	377,062					$	(2,188	)	$	(11,819	)

(a) Hedging unsecured variable rate debt.

The Company measures its derivative instruments at fair value and records them in the balance sheet as either an asset or liability. As of December 31, 2013, two interest rate swaps held asset positions and were included in other assets on the Company's consolidated balance sheet. The remaining swaps are included in other liabilities on the Company's consolidated balance sheet.

Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. The Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.

Concentration of Credit Risk

Concentrations of credit risk arise for the Company when multiple tenants of the Company are engaged in similar business activities, or are located in the same geographic region, or have similar economic features that impact in a similar manner their ability to meet contractual obligations, including those to the Company. The Company regularly monitors its tenant base to assess potential concentrations of credit risk. Management believes the current credit risk portfolio is reasonably well diversified and does not contain an unusual concentration of credit risk. No tenant accounted for 10% or more of the Company’s rents during 2013, 2012 and 2011. Conditions in the general economy and the global credit markets have had a significant adverse effect on numerous industries. The Company has tenants concentrated in various industries that may be experiencing adverse effects from the current economic conditions and the Company could be adversely affected if such tenants were to default under their leases.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41620-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579240-113959

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624177-113959

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80784-113994

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41641-113959

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624258-113959

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5708775-113959

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4J
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5708773-113959

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41635-113959

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4E
-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624181-113959

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41638-113959

Reference 20: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Discontinued Operations

12 Months Ended

Dec. 31, 2013

Discontinued Operations and Disposal Groups [Abstract]

DISCONTINUED OPERATIONS

For the years ended December 31, 2013, 2012 and 2011, income from discontinued operations relates to an aggregate of 32 properties containing approximately 2.3 million net rentable square feet that the Company has sold since January 1, 2011.

The following table summarizes revenue and expense information for the properties sold which qualify for discontinued operations reporting since January 1, 2011 (in thousands):



	Years ended December 31,
	2013		2012		2011
Revenue:
Rents	$	4,754	$	28,678	$	43,050
Tenant reimbursements	355		2,353		5,030
Termination fees	—		11		75
Other	123		378		110
Total revenue	5,232		31,420		48,265
Expenses:
Property operating expenses	1,839		8,687		13,940
Real estate taxes	649		3,468		5,356
Depreciation and amortization	1,921		10,208		16,178
Total operating expenses	4,409		22,363		35,474
Other income:
Interest income	2		7		3
Income from discontinued operations before gain on sale of interests in real estate	825		9,064		12,794
Net gain on disposition of discontinued operations	3,382		34,774		7,047
Income from discontinued operations	$	4,207	$	43,838	$	19,841

Discontinued operations have not been segregated in the consolidated statements of cash flows. Therefore, amounts for certain captions will not agree with respective data in the consolidated statements of operations.

- Definition

The entire disclosure for the facts and circumstances leading to the completed or expected disposal, manner and timing of disposal, the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the segment in which the disposal group was reported, and the classification (whether sold or classified as held for sale) and carrying value of the assets and liabilities comprising the disposal group. Includes all disposal groups, including those classified as components of the entity (discontinued operations).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1436-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1474-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1510-107760

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1020-107759

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1012-107759

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2443-110228

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2941-110230

+ Details

Non Controlling Interests in The Parent Company	12 Months Ended
Non Controlling Interests in The Parent Company	Dec. 31, 2013
Noncontrolling Interest [Abstract]
NON-CONTROLLING INTERESTS IN THE PARENT COMPANY	NON-CONTROLLING INTERESTS IN THE PARENT COMPANY'S FINANCIAL STATEMENTS Non-controlling interests in the Parent Company’s financial statements relate to redeemable common limited partnership interests in the Operating Partnership held by parties other than the Parent Company and properties which are consolidated but not wholly owned. Operating Partnership The aggregate book value of the non-controlling interests associated with the redeemable common limited partnership interests that were consolidated in the accompanying consolidated balance sheet of the Parent Company as of December 31, 2013 and December 31, 2012, was $20.3 million and $21.2 million, respectively. The Parent Company believes that the aggregate settlement value of these interests (based on the number of units outstanding and the closing price of the common shares on the balance sheet date) was approximately $24.8 million and $22.5 million, respectively, as of December 31, 2013 and December 31, 2012.

Beneficiaries Equity of the Parent Company

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

BENEFICIARIES' EQUITY OF THE PARENT COMPANY

BENEFICIARIES’ EQUITY OF THE PARENT COMPANY

Earnings per Share (EPS)

The following tables detail the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding):



	Year ended December 31,
	2013						2012						2011
	Basic			Diluted			Basic			Diluted			Basic			Diluted
Numerator
Income (loss) from continuing operations	$	38,982		$	38,982		$	(37,309	)	$	(37,309	)	$	(24,556	)	$	(24,556	)
Net (income) loss from continuing operations attributable to non-controlling interests	(357		)	(357		)	863			863			994			994
Amount allocable to unvested restricted shareholders	(363		)	(363		)	(376		)	(376		)	(505		)	(505		)
Preferred share dividends	(6,900		)	(6,900		)	(10,405		)	(10,405		)	(7,992		)	(7,992		)
Preferred share redemption charge	—			—			(4,052		)	(4,052		)	—			—
Income (loss) from continuing operations available to common shareholders	31,362			31,362			(51,279		)	(51,279		)	(32,059		)	(32,059		)
Income from discontinued operations	4,207			4,207			43,838			43,838			19,841			19,841
Discontinued operations attributable to non-controlling interests	(55		)	(55		)	(797		)	(797		)	(778		)	(778		)
Discontinued operations attributable to common shareholders	4,152			4,152			43,041			43,041			19,063			19,063
Net income (loss) attributable to common shareholders	$	35,514		$	35,514		$	(8,238	)	$	(8,238	)	$	(12,996	)	$	(12,996	)
Denominator
Weighted-average shares outstanding	153,140,458			153,140,458			143,257,097			143,257,097			135,444,424			135,444,424
Contingent securities/Share based compensation	—			1,273,853			—			—			—			—
Total weighted-average shares outstanding	153,140,458			154,414,311			143,257,097			143,257,097			135,444,424			135,444,424
Earnings per Common Share:
Income (loss) from continuing operations attributable to common shareholders	$	0.20		$	0.20		$	(0.36	)	$	(0.36	)	$	(0.24	)	$	(0.24	)
Discontinued operations attributable to common shareholders	0.03			0.03			0.30			0.30			0.14			0.14
Net income (loss) attributable to common shareholders	$	0.23		$	0.23		$	(0.06	)	$	(0.06	)	$	(0.10	)	$	(0.10	)

Redeemable common limited partnership units totaling 1,763,739 in 2013, 1,845,737 in 2012, and 2,698,647 in 2011 were excluded from the diluted earnings per share computations because they are not dilutive.

The contingent securities/share based compensation impact is calculated using the treasury stock method and relates to employee awards settled in shares of the Parent Company. The effect of these securities is anti-dilutive for periods that the Parent Company incurs a net loss from continuing operations available to common shareholders and therefore is excluded from the dilutive earnings per share calculation in such periods.

Unvested restricted shares are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the years ended December 31, 2013, 2012 and 2011, earnings representing nonforfeitable dividends were allocated to the unvested restricted shares issued to the Company’s executives and other employees under the 1997 Plan.

Common and Preferred Shares

On December 10, 2013, the Parent Company declared a distribution of $0.15 per common share, totaling $23.9 million, which was paid on January 21, 2014 to shareholders of record as of January 6, 2014. On December 10, 2013, the Parent Company declared distributions on its Series E Preferred Shares to holders of record as of December 30, 2013. These shares are entitled to a preferential return of 6.90% per annum on the $25.00 per share liquidation preference. Distributions paid on January 15, 2014 to holders of Series E Preferred Shares totaled $1.7 million.

On November 5, 2013, the Parent Company commenced a continuous equity offering program (the “Offering Program”), under which it may sell, in at-the-market offerings, up to an aggregate amount of 16,000,000 common shares until November 5, 2016. This Offering Program replaced a prior continuous equity offering program which expired on March 10, 2013. The Parent Company may sell common shares in amounts and at times to be determined by the Parent Company. Actual sales will depend on a variety of factors to be determined by the Parent Company, including, among others, market conditions, the trading price of the Company’s common shares of beneficial interest and determinations by the Parent Company of the appropriate sources of funding. In conjunction with the Offering Program, the Parent Company engages sales agents who receive compensation, in aggregate, of up to 2% of the gross sales price per share sold. From inception of the Offering Program through December 31, 2013, the Parent Company has not sold any shares under the program, resulting in 16,000,000 remaining shares available for sale.

On April 10, 2013, the Parent Company closed a public offering of 12,650,000 common shares, inclusive of 1,650,000 common shares issued upon exercise by the underwriters of the option granted to them to purchase additional shares. The Parent Company contributed the net proceeds from the sale of shares, amounting to $181.5 million after deducting underwriting discounts and commissions and other offering expenses, to the Operating Partnership in exchange for partnership units of the Operating Partnership. The Operating Partnership continues to use the net proceeds for working capital, capital expenditures and other general corporate purposes, which may include acquisitions, developments and the repayment, repurchase and refinancing of debt.

Common Share Repurchases

The Parent Company maintains a share repurchase program under which it may repurchase its common shares from time to time in accordance with limits set by the Board of Trustees.

The Parent Company did not repurchase any shares under the share repurchase program during the year-ended December 31, 2013. As of December 31, 2013, the Parent Company may purchase an additional 539,200 shares under the program.

Repurchases may be made from time to time in the open market or in privately negotiated transactions, subject to market conditions and compliance with legal requirements. The share repurchase program does not contain any time limitation and does not obligate the Parent Company to repurchase any shares. The Parent Company may discontinue the program at any time.

Partners Equity of The Operating Partnership

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

PARTNERS' EQUITY OF THE OPERATING PARTNERSHIP

PARTNERS’ EQUITY OF THE OPERATING PARTNERSHIP

Earnings per Common Partnership Unit

The following tables detail the number of units and net income used to calculate basic and diluted earnings per common partnership unit (in thousands, except unit and per unit amounts; results may not add due to rounding):



	Year ended December 31,
	2013						2012						2011
	Basic			Diluted			Basic			Diluted			Basic			Diluted
Numerator
Income (loss) from continuing operations	$	38,982		$	38,982		$	(37,309	)	$	(37,309	)	$	(24,556	)	$	(24,556	)
Amount allocable to unvested restricted unitholders	(363		)	(363		)	(376		)	(376		)	(505		)	(505		)
Preferred unit dividends	(6,900		)	(6,900		)	(10,405		)	(10,405		)	(7,992		)	(7,992		)
Preferred unit redemption charge	—			—			(4,052		)	(4,052		)	—			—
Income (loss) from continuing operations available to common unitholders	31,719			31,719			(52,142		)	(52,142		)	(33,053		)	(33,053		)
Discontinued operations attributable to common unitholders	4,207			4,207			43,838			43,838			19,841			19,841
Net income (loss) attributable to common unitholders	$	35,926		$	35,926		$	(8,304	)	$	(8,304	)	$	(13,212	)	$	(13,212	)
Denominator
Weighted-average units outstanding	154,929,545			154,929,545			145,883,217			145,883,217			145,118,841			145,118,841
Contingent securities/Share based compensation	—			1,273,853			—			—			—			—
Total weighted-average units outstanding	154,929,545			156,203,398			145,883,217			145,883,217			145,118,841			145,118,841
Earnings per Common Partnership Unit:
Income (loss) from continuing operations attributable to common unitholders	$	0.20		$	0.20		$	(0.36	)	$	(0.36	)	$	(0.23	)	$	(0.23	)
Discontinued operations attributable to common unitholders	0.03			0.03			0.30			0.30			0.14			0.14
Net income (loss) attributable to common unitholders	$	0.23		$	0.23		$	(0.06	)	$	(0.06	)	$	(0.09	)	$	(0.09	)

Unvested restricted units are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the years ended December 31, 2013, 2012 and 2011, earnings representing nonforfeitable dividends were allocated to the unvested restricted units.

Common Partnership Units and Preferred Mirror Units

The Operating Partnership issues partnership units to the Parent Company in exchange for the contribution of the net proceeds of any equity security issuance by the Parent Company. The number and terms of such partnership units correspond to the number and terms of the related equity securities issued by the Parent Company. In addition, the Operating Partnership may also issue separate classes of partnership units. Historically, the Operating Partnership has had the following types of partnership units outstanding (i) Preferred Partnership Units which have been issued to parties other than the Parent Company (ii) Preferred Mirror Partnership Units which have been issued to the Parent Company and (iii) Common Partnership Units which include both interests held by the Parent Company and those held by other limited partners. Each of these interests is described in more detail below.

Preferred Mirror Partnership Units

In exchange for the proceeds received in corresponding offerings by the Parent Company of preferred shares of beneficial interest, the Operating Partnership has issued to the Parent Company a corresponding amount of Preferred Mirror Partnership Units with terms consistent with that of the preferred securities issued by the Parent Company.

Common Partnership Units (Redeemable and General)

The Operating Partnership has two classes of Common Partnership Units: (i) Class A Limited Partnership Interest which are held by both the Parent Company and outside third parties and (ii) General Partnership Interests which are held by the Parent Company (collectively, the Class A Limited Partnership Interest, and General Partnership Interests are referred to as “Common Partnership Units”). The holders of the Common Partnership Units are entitled to share in cash distributions from, and in profits and losses of, the Operating Partnership, in proportion to their respective percentage interests, subject to preferential distributions on the preferred mirror units and the preferred units.

The Common Partnership Units held by the Parent Company (comprised of both General Partnership Units and Class A Limited Partnership Units) are presented as partner’s equity in the consolidated financial statements. Class A Limited Partnership Interest held by parties other than the Parent Company are redeemable at the option of the holder for a like number of common shares of the Parent Company, or cash, or a combination thereof, at the election of the Parent Company. Because the form of settlement of these redemption rights are not within the control of the Operating Partnership, these Common Partnership Units have been excluded from partner’s equity and are presented as redeemable limited partnership units measured at the potential cash redemption value as of the end of the periods presented based on the closing market price of the Parent Company’s common shares at December 31, 2013, 2012 and 2011, which was $14.09, $12.19, $9.50, respectively. As of December 31, 2013 and 2012, 1,763,739 and 1,845,737 of Class A Units, respectively, were outstanding and owned by outside limited partners of the Operating Partnership.

On December 10, 2013, the Operating Partnership declared a distribution of $0.15 per common partnership unit, totaling $23.9 million, which was paid on January 21, 2014 to unitholders of record as of January 6, 2014.

On December 10, 2013, the Operating Partnership declared distributions on its Series E-Linked Preferred Mirror Units to holders of record as of December 30, 2013. These units are entitled to a preferential return of 6.90% per annum on the $25.00 per unit liquidation preference. Distributions paid on January 15, 2014 to holders of Series E-Linked Preferred Mirror Units totaled $1.7 million.

On November 5, 2013, the Parent Company commenced a continuous equity offering program (the “Offering Program”), under which it may sell, in at-the-market offerings, up to an aggregate amount of 16,000,000 common shares until November 5, 2013. This Offering Program replaced a prior continuous equity offering program which expired on March 10, 2013. The Parent Company may sell common shares in amounts and at times to be determined by the Parent Company. Actual sales will depend on a variety of factors to be determined by the Parent Company, including, among others, market conditions, the trading price of the Company’s common shares of beneficial interest and determinations by the Parent Company of the appropriate sources of funding. In conjunction with the Offering Program, the Parent Company engages sales agents who receive compensation, in aggregate, of up to 2% of the gross sales price per share sold. From inception of the Offering Program through December 31, 2013, the Parent Company has not sold any shares under the program, resulting in 16,000,000 remaining shares available for sale. Generally, the Parent Company contributes the net proceeds from the sales to the Operating Partnership, which the Operating Partnership in turn uses for general corporate purposes.

Common Unit Repurchases

The Parent Company did not repurchase any shares under its share repurchase program during the year-ended December 31, 2013 and accordingly, during the year-ended December 31, 2013, the Operating Partnership did not repurchase any units in connection with the Parent Company’s share repurchase program.

Share Based and Deferred Compensation

12 Months Ended

Dec. 31, 2013

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

SHARE BASED AND DEFERRED COMPENSATION

SHARE BASED COMPENSATION, 401(k) PLAN AND DEFERRED COMPENSATION

Stock Options

At December 31, 2013, options exercisable for 2,983,569 common shares were outstanding under the Parent Company's shareholder approved equity incentive plan. There were 184,429 options unvested as of December 31, 2013 and $0.1 million of unrecognized compensation expense associated with these options to be recognized over a weighted average of 0.2 years. During the years ended December 31, 2013, 2012 and 2011 the Company recognized compensation expense related to unvested options of $0.7 million, $1.6 million, and $1.4 million, respectively. During the years ended December 31, 2013, 2012 and 2011, the Company also capitalized a $0.1 million, $0.5 million and $0.4 million, respectively, of compensation expense as part of the Company’s review of employee salaries eligible for capitalization.

Option activity as of December 31, 2013 and changes during the year-ended December 31, 2013 were as follows:



	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at January 1, 2013	3,337,549		$	14.85	5.95	$	—
Exercised	(236,318	)	$	9.86
Forfeited/Expired	(117,662	)	$	18.61
Outstanding at December 31, 2013	2,983,569		$	15.50	5.15	$	—
Vested/Exercisable at December 31, 2013	2,799,140		$	15.74	5.05	$	—

401(k) Plan

The Company sponsors a 401(k) defined contribution plan for its employees. Each employee may contribute up to 100% of annual compensation, subject to specific limitations under the Internal Revenue Code. At its discretion, the Company can make matching contributions equal to a percentage of the employee’s elective contribution and profit sharing contributions. Employees automatically vest in employer contributions. The Company contributions were $0.4 million in each of 2013, 2012 and 2011.

Restricted Share Awards

As of December 31, 2013, 563,713 restricted shares were outstanding under the 1997 Plan and vest over three to seven years from the initial grant date. The remaining compensation expense to be recognized at December 31, 2013 was approximately $1.9 million, and is expected to be recognized over a weighted average remaining vesting period of 1.1 years. During 2013 the Company recognized compensation expense related to outstanding restricted shares of $3.2 million, of which $0.6 million was capitalized as part of the Company’s review of employee salaries eligible for capitalization. For the years ended December 31, 2012 and 2011, the Company recognized $3.4 million (of which $0.9 million was capitalized) and $3.2 million (of which $0.7 million was capitalized), respectively, of compensation expense included in general and administrative expense in the respective periods related to outstanding restricted shares.

The following table summarizes the Company’s restricted share activity during the year-ended December 31, 2013:



	Shares		Weighted Average Grant Date Fair value
Non-vested at January 1, 2013	597,708		$	12.57
Granted	182,576		13.13
Vested	(208,306	)	13.13
Forfeited	(8,265	)	11.41
Non-vested at December 31, 2013	563,713		$	12.56

On February 25, 2013, the Compensation Committee of the Company’s Board of Trustees awarded 157,208 restricted shares to the Company’s executives. The restricted shares will cliff vest after three years from the grant date. The vesting of the restricted shares is also subject to acceleration upon a change in control or if the recipient of the award were to die, become disabled, or be terminated without cause or retire in a qualifying retirement. Qualifying retirement means the recipient’s voluntary termination of employment after reaching at least age 57 and accumulating at least 15 years of service with the Company. In accordance with the accounting standard for stock-based compensation, the Company amortizes stock-based compensation costs through the qualifying retirement dates for those executives who meet the conditions for qualifying retirement during the scheduled vesting period.

Restricted Performance Share Units Plan

On each of February 25, 2013, March 1, 2012 and March 2, 2011, the Compensation Committee of the Parent Company’s Board of Trustees awarded an aggregate of 231,093, 242,122, and 113,256 share-based awards, respectively, to its executives. These awards are referred to as Restricted Performance Share Units, or RPSUs. The RPSUs represent the right to earn common shares. The number of common shares, if any, deliverable to award recipients depends on the Company’s performance based on its total return to shareholders during the three years measurement period that commenced on January 1, 2013 (in the case of the February 25, 2013 awards), January 1, 2012 (in the case of the March 1, 2012 awards), and January 1, 2011 (in the case of the March 2, 2011 awards), and that ends on December 31, 2015, December 31, 2014 or December 31, 2013 (as applicable) or, if earlier, the date of a change of control. In the case of the awards made on February 25, 2013 and March 1, 2012, the Company's performance is compared to the shareholder return of REITs within an index over the measurement period for 50% of the RPSUs awarded on that date, with the remaining 50% being compared to the total shareholder return of REITs within the Company's proxy peer group over such period. In the case of the awards made on March 2, 2011, the Company's performance is compared to the total shareholder return of REITs within an index over the performance period. The vesting of RPSUs is contingent upon the continued employment of the participants through the performance periods (with exceptions for death, disability and qualifying retirement). Dividends are deemed credited to the performance units accounts and are applied to “acquire” additional RPSUs for the account of the unit holder at the price per common share on the dividend payment date. If earned, RPSUs will be settled in common shares in an amount that reflects both the number of RPSUs in the holder’s account at the end of the applicable measurement period and the Company’s total return to shareholders during the applicable three year measurement period relative to the total shareholder returns of the REITs within the index or peer group, as applicable.

On the date of each grant, the RPSUs were valued using a Monte Carlo simulation. The fair values of the 2013, 2012 and 2011 awards on the grant dates were $4.1 million, $4.1 million and $2.0 million, respectively. The fair values of each award are being amortized over the three year cliff vesting period. The vesting of RPSUs is subject to acceleration upon a change in control or if the recipient of the award were to die, become disabled or retire in a qualifying retirement prior to the vesting date. In the case of two of the Company's executives who have employment agreements with the Company, the vesting of the restricted shares is also subject to acceleration if either executive were to be terminated without cause or resign for good reason. Qualifying retirement means the recipient’s voluntary termination of employment after reaching age 57 years and accumulating at least 15 years of service with the Company. In accordance with the accounting standard for stock-based compensation, the Company amortizes stock-based compensation costs through the qualifying retirement date for those executives who meet the conditions for qualifying retirement during the schedule vesting period.

For the year-ended December 31, 2013, the Company recognized total compensation expense for the 2013, 2012 and 2011 RPSU awards of $4.4 million of which $0.8 million was capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation. For the year-ended December 31, 2012, the Company recognized total compensation expense for the 2012, 2011 and 2010 awards of $3.5 million related to this plan, of which $1.2 million was capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation. During the year ended December 31, 2011, the Company recognized total compensation expense for the 2011, 2010, and 2009 awards of $1.7 million related to this plan, of which $0.5 million was capitalized as part of the Company’s policies for capitalizing eligible portions of employee compensation.

A total of 64,678 common shares vested on December 31, 2012 (the end of the three-year measurement period for the linked RPSUs) and were delivered to holders of the RPSUs on March 1, 2013 in settlement of the RPSUs. Holders of these RPSUs also received cash dividend equivalents to the cash dividends paid on common shares on February 8, 2013.

Employee Share Purchase Plan

The Parent Company’s shareholders approved the 2007 Non-Qualified Employee Share Purchase Plan (the “ESPP”), which is intended to provide eligible employees with a convenient means to purchase common shares of the Parent Company through payroll deductions and voluntary cash purchases at an amount equal to 85% of the average closing price per share for a specified period. Under the plan document, the maximum participant contribution for the 2013 plan year is limited to the lesser of 20% of compensation or $50,000. The ESPP allows the Parent Company to make open market purchases, which reflects all purchases made under the plan to date. In addition, the number of shares separately reserved for issuance under the ESPP is 1.25 million. During the year-ended December 31, 2013, employees made purchases under the ESPP of $0.3 million and the Company recognized $0.1 million of compensation expense related to the ESPP. During the years-ended December 31, 2012 and 2011, employees made purchases of $0.4 million under the ESPP, and the Company recognized $0.1 million of compensation expense related to the ESPP. Compensation expense represents the 15% discount on the purchase price. The Board of Trustees of the Parent Company may terminate the ESPP at its sole discretion at any time.

Deferred Compensation

In January 2005, the Parent Company adopted a Deferred Compensation Plan (the “Plan”) that allows trustees and certain key employees to voluntarily defer compensation. Compensation expense is recorded for the deferred compensation and a related liability is recognized. Participants may elect designated benchmark investment options for the notional investment of their deferred compensation. The deferred compensation obligation is adjusted for deemed income or loss related to the investments selected. At the time the participants defer compensation, the Company records a liability, which is included in the Company’s consolidated balance sheet. The liability is adjusted for changes in the market value of the participant-selected investments at the end of each accounting period, and the impact of adjusting the liability is recorded as an increase or decrease to compensation cost.

The Company has purchased mutual funds which can be utilized as a funding source for the Company’s obligations under the Plan. Participants in the Plan have no interest in any assets set aside by the Company to meet its obligations under the Plan. For the years-ended December 31, 2013, 2012 and 2011 the Company recorded net increases in compensation costs of $0.2 million, $0.3 million and $0.1 million, respectively, net of investments in the company-owned policies and mutual funds.

Participants in the Plan may elect to have all or a portion of their deferred compensation invested in the Company’s common shares. The Company holds these shares in a rabbi trust, which is subject to the claims of the Company’s creditors in the event of the Company’s bankruptcy or insolvency. The Plan does not permit diversification of a participant’s deferral allocated to the Company common shares and deferrals allocated to Company common shares can only be settled with a fixed number of shares. In accordance with the accounting standard for deferred compensation arrangements where amounts earned are held in a rabbi trust and invested, the deferred compensation obligation associated with the Company’s common shares is classified as a component of shareholder’s equity and the related shares are treated as shares to be issued and are included in total shares outstanding. At December 31, 2013 and 2012, 0.3 million of such shares were included in total shares outstanding. Subsequent changes in the fair value of the common shares are not reflected in operations or shareholders’ equity of the Company.

Distributions

12 Months Ended

Dec. 31, 2013

Distributions [Abstract]

Stockholders' Equity Note Disclosure [Text Block]

DISTRIBUTIONS



	Years ended December 31,
	2013			2012			2011
	(in thousands, except per share amounts)
Common Share Distributions:
Ordinary income	$	0.52		$	0.39		$	0.37
Capital gain	—			—			—
Non-taxable distributions	0.08			0.21			0.23
Distributions per share	$	0.60		$	0.60		$	0.60
Percentage classified as ordinary income	87.00		%	65.00		%	61.67		%
Percentage classified as capital gain	—		%	—		%	—		%
Percentage classified as non-taxable distribution	13.00		%	35.00		%	38.33		%
Preferred Share Distributions:
Total distributions declared	$	6,900		$	10,405		$	7,992
Percentage classified as ordinary income	100.00		%	100.00		%	100.00		%

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph d
-Article 4

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Article 4

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Tax Credit Transactions	12 Months Ended
Tax Credit Transactions	Dec. 31, 2011
Income Tax Disclosure [Abstract]
TAX CREDIT TRANSACTIONS	TAX CREDIT TRANSACTIONS Historic Tax Credit Transaction On November 17, 2008, the Company closed a transaction with US Bancorp (“USB”) related to the historic rehabilitation of the IRS Philadelphia Campus, a 862,692 square foot office building that is 100% leased to the IRS. On August 27, 2010, the Company completed the development of the IRS Philadelphia Campus and the IRS lease commenced. In connection with this completed development project, USB contributed to the Company $64.1 million of total project costs. In exchange for its contributions to the development of the IRS Philadelphia Campus, USB is entitled to substantially all of the benefits derived from the tax rehabilitation credits available under section 47 of the Internal Revenue Code. USB does not have a material interest in the underlying economics of the property. This transaction includes a put/call provision whereby the Company may be obligated or entitled to repurchase USB’s interest in the IRS Philadelphia Campus. The Company believes the put will be exercised and the amount attributed to that puttable non-controlling interest obligation is included in other liabilities and is being accreted to the expected fixed put price. Based on the contractual arrangements that obligate the Company to deliver tax benefits and provide other guarantees to USB and that entitle the Company through fee arrangements to receive substantially all available cash flow from the IRS Philadelphia Campus, the Company concluded that the IRS Philadelphia Campus should be consolidated. The Company also concluded that capital contributions received from USB, in substance, are consideration that the Company receives in exchange for its obligation to deliver tax credits and other tax benefits to USB. These receipts other than the amounts allocated to the put obligation will be recognized as revenue in the consolidated financial statements beginning when the obligation to USB is relieved which occurs upon delivery of the expected tax benefits net of any associated costs. The tax credit is subject to 20% recapture per year beginning one year after the completion of the IRS Philadelphia Campus. The total remaining USB contributions presented within the Company’s consolidated balance sheet amounted to $26.8 million as of December 31, 2013 and $39.1 million as of December 31, 2012. The contributions were recorded net of the amount allocated to non-controlling interest as described above of $2.8 million and $2.6 million at the end of the years ended December 31, 2013 and December 31, 2012, respectively, with the remaining balance being presented within deferred income. Beginning in September 2011 to September 2015, the Company recognized and will recognize the cash received as revenue net of allocated expenses over the five year credit recapture period as defined in the Internal Revenue Code within other income (expense) in its consolidated statements of operations. During the years-ended December 31, 2013 and 2012, the Company recognized $11.9 million of the cash received as revenue, net of $0.5 million of allocated expenses within other income (expense) in its consolidated statements of operations. Direct and incremental costs incurred in structuring the transaction are deferred and will be recognized as expense in the consolidated financial statements upon the recognition of the related revenue as discussed above. The deferred cost at December 31, 2013 and December 31, 2012 is $1.0 million and $1.6 million, respectively, and are included in other assets in the Company’s consolidated balance sheet. Amounts included in interest expense related to the accretion of the non-controlling interest liability and the 2% return expected to be paid to USB on its non-controlling interest aggregate to $1.4 million for year-ended December 31, 2013 and $1.3 million for each of the years ended December 31, 2012 and 2011. New Markets Tax Credit Transaction On December 30, 2008, the Company entered into a transaction with USB related to the Cira South Garage in Philadelphia, Pennsylvania and expects to receive a net benefit of $7.8 million under a qualified New Markets Tax Credit Program (“NMTC”). The NMTC was provided for in the Community Renewal Tax Relief Act of 2000 (the “Act”) and is intended to induce investment capital in under-served and impoverished areas of the United States. The Act permits taxpayers (whether companies or individuals) to claim credits against their Federal income taxes for up to 39% of qualified investments in qualified, active low-income businesses or ventures. USB contributed $13.3 million into the development of the Cira South Garage and as such it is entitled to substantially all of the benefits derived from the tax credit, but it does not have a material interest in the underlying economics of the Cira South Garage. This transaction also includes a put/call provision whereby the Company may be obligated or entitled to repurchase USB’s interest. The Company believes the put will be exercised and an amount attributed to that obligation is included in other liabilities and is being accreted to the expected fixed put price. The said put price is insignificant. Based on the contractual arrangements that obligate the Company to deliver tax benefits and provide various other guarantees to USB, the Company concluded that the investment entities established to facilitate the NMTC transaction should be consolidated. The USB contribution of $13.3 million is included in deferred income on the Company’s consolidated balance sheets at each of the years ended December 31, 2013 and December 31, 2012. The USB contribution other than the amount allocated to the put obligation will be recognized as income in the consolidated financial statements when the tax benefits are delivered without risk of recapture to the tax credit investors and the Company’s obligation is relieved. The Company anticipates that it will recognize the net cash received as revenue within other income/expense in the year ended December 31, 2015. The NMTC is subject to 100% recapture for a period of seven years as provided in the Internal Revenue Code. The Company expects that the put/call provision will be exercised in 2017. Direct and incremental costs incurred in structuring the transaction are deferred and will be recognized as expense in the consolidated financial statements upon the recognition of the related revenue as discussed above. The deferred cost at each of the years ended December 31, 2013 and December 31, 2012 is $5.3 million, and is included in other assets in the Company’s consolidated balance sheet.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2013

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Comprehensive Income (Loss) Note [Text Block]

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

The following table details the components of accumulated other comprehensive income (loss) of the Parent Company and the Operating Partnership as of and for the three years ended December 31, 2013 (in thousands):



Parent Company	Cash Flow Hedges
Balance at January 1, 2011	$	(1,945	)
Change during year	(4,499		)
Non-controlling interest — consolidated real estate venture partner’s share of unrealized (gains)/losses on derivative financial instruments	212
Reclassification adjustments for (gains) losses reclassified into operations	153
Balance at December 31, 2011	$	(6,079	)
Change during year	(7,338		)
Non-controlling interest — consolidated real estate venture partner’s share of unrealized (gains)/losses on derivative financial instruments	187
Settlement of interest rate swaps	(2,985		)
Reclassification adjustments for (gains) losses reclassified into operations	297
Balance at December 31, 2012	$	(15,918	)
Change during year	12,789
Non-controlling interest — consolidated real estate venture partner’s share of unrealized (gains)/losses on derivative financial instruments	(152		)
Reclassification adjustments for (gains) losses reclassified into operations	286
Balance at December 31, 2013	$	(2,995	)



Operating Partnership	Cash Flow Hedges
Balance at January 1, 2011	$	(2,080	)
Change during year	(4,499		)
Reclassification adjustments for (gains) losses reclassified into operations	153
Balance at December 31, 2011	$	(6,426	)
Change during year	(7,338		)
Settlement of interest rate swaps	(2,985		)
Reclassification adjustments for (gains) losses reclassified into operations	297
Balance at December 31, 2012	$	(16,452	)
Change during year	12,789
Reclassification adjustments for (gains) losses reclassified into operations	286
Balance at December 31, 2013	$	(3,377	)

Over time, the unrealized gains and losses held in Accumulated Other Comprehensive Income (“AOCI”) will be reclassified to interest expense when the related hedged items are recognized in earnings. The current balance held in AOCI is expected to be reclassified to interest expense for realized losses on forecasted debt transactions over the related term of the debt obligation, as applicable.

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669619-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e640-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e716-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e709-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e637-108580

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e681-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Segment Information

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

SEGMENT INFORMATION

During the year ended December 31, 2013, the Company was managing its portfolio within seven segments: (1) Pennsylvania, (2) Philadelphia Central Business District (CBD), (3) Metropolitan Washington D.C., (4) New Jersey/Delaware, (5) Richmond, Virginia, (6) Austin, Texas and (7) California. The Pennsylvania segment includes properties in Chester, Delaware, and Montgomery counties in the Philadelphia suburbs. The Philadelphia CBD segment includes properties located in the City of Philadelphia in Pennsylvania. The Metropolitan Washington, D.C. segment includes properties in Northern Virginia and southern Maryland. The New Jersey/Delaware segment includes properties in Burlington and Camden counties in New Jersey and in New Castle county in the state of Delaware. The Richmond, Virginia segment includes properties primarily in Albemarle, Chesterfield, Goochland and Henrico counties and one property in Durham, North Carolina. The Austin, Texas segment includes properties in Austin. On October 16, 2013, seven properties within the Austin portfolio were contributed to a newly formed real estate venture. After contributing the properties, the Company wholly owns only one property in Austin, Texas (For additional information, see Note 4). The California segment includes properties in Oakland, Concord, and Carlsbad. The corporate group is responsible for cash and investment management, development of certain real estate properties during the construction period, and certain other general support functions. Land held for development and construction in progress are transferred to operating properties by region upon completion of the associated construction or project.

Segment information for the three years ended December 31, 2013, 2012 and 2011 are as follows (in thousands):



	Pennsylvania Suburbs		Philadelphia CBD		Metropolitan Washington, D.C.			New Jersey/Delaware		Richmond, Virginia		Austin, Texas (a)			California		Corporate			Total
2013
Real estate investments, at cost:
Operating properties	$	1,199,105	$	1,300,666	$	1,214,965		$	414,716	$	310,397	$	36,856		$	192,584	$	—		$	4,669,289
Construction-in-progress																	74,174			74,174
Land inventory																	93,351			93,351
Total revenue	$	153,426	$	146,081	$	116,048		$	60,262	$	35,058	$	31,451		$	18,369	$	1,515		$	562,210
Property operating expenses, real estate taxes and third party management expenses	54,506		55,702		42,641			29,981		14,916		13,298			9,411		1,314			221,769
Net operating income	$	98,920	$	90,379	$	73,407		$	30,281	$	20,142	$	18,153		$	8,958	$	201		$	340,441

Investment in real estate ventures, at equity	$	17,272	$	19,975	$	59,905		$	—	$	1,400	$	81,960		$	—	$	—		$	180,512
Equity in income of real estate ventures	$	925	$	1,547	$	130		$	1,245	$	381	$	(564	)	$	—	$	—		$	3,664

2012
Real estate investments, at cost:
Operating properties	$	1,178,730	$	988,590	$	1,193,200		$	546,644	$	309,923	$	285,346		$	223,736	$	—		$	4,726,169
Construction-in-progress																	48,950			48,950
Land inventory																	102,439			102,439
Total revenue	$	150,075	$	131,592	$	107,656		$	59,671	$	35,701	$	32,379		$	17,463	$	1,142		$	535,679
Property operating expenses, real estate taxes and third party management expenses	52,657		50,787		41,485			28,506		14,484		13,951			9,043		(65		)	210,848
Net operating income	$	97,418	$	80,805	$	66,171		$	31,165	$	21,217	$	18,428		$	8,420	$	1,207		$	324,831

Investment in real estate ventures, at equity	$	33,160	$	27,859	$	49,169		$	17,294	$	1,245	$	64,828		$	—	$	—		$	193,555
Equity in income of real estate ventures	$	520	$	1,113	$	(648	)	$	1,803	$	269	$	(316	)	$	—	$	—		$	2,741

2011
Operating properties	$	1,218,071	$	953,870	$	1,255,803		$	545,657	$	307,698	$	257,694		$	254,287	$	—		$	4,793,080
Construction-in-progress																	25,083			25,083
Land inventory																	109,008			109,008
Total revenue	$	148,887	$	125,366	$	119,255		$	58,960	$	36,789	$	30,894		$	16,692	$	1,725		$	538,568
Property operating expenses, real estate taxes and third party management expenses	54,734		48,831		45,135			30,564		14,739		13,034			9,407		347			216,791
Net operating income	$	94,153	$	76,535	$	74,120		$	28,396	$	22,050	$	17,860		$	7,285	$	1,378		$	321,777

Investment in real estate ventures, at equity	$	5,264	$	13,397	$	24,671		$	6,168	$	1,163	$	65,144		$	—	$	—		$	115,807
Equity in income of real estate ventures	$	1,861	$	466	$	(277	)	$	1,157	$	510	$	58		$	—	$	—		$	3,775

(a) On October 16, 2013 seven properties from the Austin portfolio were contributed to a newly formed real estate venture. Accordingly, the Company's 50% interest in the financial results of these seven properties for the period subsequent to October 16, 2013 is reported as a component of 'Equity in income of real estate ventures' in the Company's consolidated statements of operations and, as a result, no longer included as a component of net operating income. The Company acquired Four Points Centre in Austin, TX on December 19, 2013 and the financial results for this property are included in net operating income for the period owned. For additional information, see Notes 3 and 4 to our consolidated financial statements.

Net operating income (“NOI”) is defined as total revenue less property operating expenses, real estate taxes and third party management expenses. Segment NOI includes revenue, real estate taxes and property operating expenses directly related to operation and management of the properties owned and managed within the respective geographical region. Segment NOI excludes property level depreciation and amortization, revenue and expenses directly associated with third party real estate management services, expenses associated with corporate administrative support services, and inter-company eliminations. NOI also does not reflect general and administrative expenses, interest expenses, real estate impairment losses, depreciation and amortization costs, capital expenditures and leasing costs. Trends in development and construction activities that could materially impact the Company’s results from operations are also not reflected in NOI. All companies may not calculate NOI in the same manner. NOI is the measure that is used by the Company to evaluate the operating performance of its real estate assets by segment. The Company also believes that NOI provides useful information to investors regarding its financial condition and results of operations because it reflects only those income and expenses recorded at the property level. The Company believes that net income, as defined by GAAP, is the most appropriate earnings measure. The following is a reconciliation of consolidated NOI to consolidated net income (loss), as defined by GAAP:



	Years Ended December 31,
	2013			2012			2011

Consolidated net operating income	$	340,441		$	324,831		$	321,777
Less:
Interest expense	(121,937		)	(132,939		)	(131,405		)
Interest expense - amortization of deferred financing costs	(4,676		)	(6,208		)	(4,991		)
Interest expense - financing obligation	(972		)	(850		)	—
Depreciation and amortization	(197,021		)	(188,382		)	(202,933		)
General and administrative expenses	(27,628		)	(25,413		)	(24,602		)
Plus:
Interest income	1,044			3,008			1,810
Historic tax credit transaction income	11,853			11,840			12,026
Recognized hedge activity	—			(2,985		)	—
Equity in income of real estate ventures	3,664			2,741			3,775
Net gain from remeasurement of investments in real estate ventures	6,866			—			—
Net gain on sales of interests in real estate	—			—			2,985
Net loss on sale of undepreciated real estate	(137		)	—			—
Net gain (loss) on real estate venture transactions	29,604			(950		)	(222		)
Loss on early extinguishment of debt	(2,119		)	(22,002		)	(2,776		)
Income (loss) from continuing operations	38,982			(37,309		)	(24,556		)
Income from discontinued operations	4,207			43,838			19,841
Net income (loss)	$	43,189		$	6,529		$	(4,715	)

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8906-108599

+ Details

Operating Leases

12 Months Ended

Dec. 31, 2013

Operating Leases [Abstract]

Operating Leases of Lessor Disclosure [Text Block]

OPERATING LEASES

The Company leases properties to tenants under operating leases with various expiration dates extending to 2030. Minimum future rentals on non-cancelable leases at December 31, 2013 are as follows (in thousands):



Year	Minimum Rent
2014	$	471,918
2015	457,315
2016	416,467
2017	358,368
2018	299,619
Thereafter	1,403,003

Total minimum future rentals presented above do not include amounts to be received as tenant reimbursements for operating costs

Commitments and Contingencies

12 Months Ended

Dec. 31, 2013

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Legal Proceedings

The Company is involved from time to time in litigation on various matters, including disputes with tenants and disputes arising out of agreements to purchase or sell properties. Given the nature of the Company’s business activities, these lawsuits are considered routine to the conduct of its business. The result of any particular lawsuit cannot be predicted, because of the very nature of litigation, the litigation process and its adversarial nature, and the jury system. The Company will establish reserves for specific legal proceedings when we determine that the likelihood of an unfavorable outcome is probable and when the amount of loss is reasonably estimable. The Company does not expect that the liabilities, if any, that may ultimately result from such legal actions will have a material adverse effect on the consolidated financial position, results of operations or cash flows of the Company.

Letters-of-Credit

Under certain mortgages, the Company has funded required leasing and capital reserve accounts for the benefit of the mortgage lenders with letters-of-credit. There were no associated letters-of-credit at December 31, 2013 and December 31, 2012. Certain of the tenant rents at properties that secure these mortgage loans are deposited into the loan servicer’s depository accounts, which are used to fund debt service, operating expenses, capital expenditures and the escrow and reserve accounts, as necessary. Any excess cash is included in cash and cash equivalents.

Environmental

As an owner of real estate, the Company is subject to various environmental laws of federal, state, and local governments. The Company’s compliance with existing laws has not had a material adverse effect on its financial condition and results of operations, and the Company does not believe it will have a material adverse effect in the future. However, the Company cannot predict the impact of unforeseen environmental contingencies or new or changed laws or regulations on its current Properties or on properties that the Company may acquire.

Ground Rent

Future minimum rental payments under the terms of all non-cancellable ground leases under which the Company is the lessee are expensed on a straight-line basis regardless of when payments are due. The Company’s ground leases have remaining lease terms ranging from 15 to 75 years. Minimum future rental payments on non-cancelable leases at December 31, 2013 are as follows (in thousands):



Year	Minimum Rent
2014	$	1,303
2015	1,303
2016	1,303
2017	1,303
2018	1,303
Thereafter	57,540
Total	64,055

The Company obtained ground tenancy rights related to two properties in Philadelphia, Pennsylvania, which provide for contingent rent participation by the lessor in certain capital transactions and net operating cash flows of the properties after certain returns are achieved by the Company. Such amounts, if any, will be reflected as contingent rent when incurred. The leases also provide for payment by the Company of certain operating costs relating to the land, primarily real estate taxes. The above schedule of future minimum rental payments does not include any contingent rent amounts or any reimbursed expenses.

Other Commitments or Contingencies

As part of the Company’s September 2004 acquisition of a portfolio of properties from The Rubenstein Company (which the Company refers to as the "TRC acquisition"), the Company acquired its interest in Two Logan Square, a 708,844 square foot office building in Philadelphia, primarily through its ownership of a second and third mortgage secured by this property. This property is consolidated, as the borrower is a variable interest entity and the Company, through its ownership of the second and third mortgages, is the primary beneficiary. The Company currently does not expect to take title to Two Logan Square until, at the earliest, September 2019. If the Company takes fee title to Two Logan Square upon a foreclosure of its mortgage, the Company has agreed to pay an unaffiliated third party that holds a residual interest in the fee owner of this property an amount equal to $2.9 million. On the TRC acquisition date, the Company recorded a liability of $0.7 million and this amount will accrete up to $2.9 million through September 2019. As of December 31, 2013, the Company had a balance of $1.6 million for this liability in its consolidated balance sheet.

The Company was audited by the Internal Revenue Service (the “IRS”) for its 2004 tax year. The audit concerned the tax treatment of the TRC acquisition in September 2004 in which the Company acquired a portfolio of properties through the acquisition of a limited partnership. On December 17, 2010, the Company received notice that the IRS proposed an adjustment to the allocation of recourse liabilities allocated to the contributor of the properties. The Company appealed the proposed adjustment and during the second quarter of 2013, the IRS finalized a settlement agreement which will not result in a material liability to the Company for federal income taxes. The contributor of partnership interests in the 2004 transaction has agreed not to assert a claim against the Company for federal income tax purposes under the tax protection agreement entered into as part of the transaction.

As part of the Company’s 2006 merger with Prentiss Properties Trust ("Prentiss"), the 2004 TRC acquisition and several of our other transactions, the Company agreed not to sell certain of the properties it acquired in transactions that would trigger taxable income to the former owners. In the case of the TRC acquisition, the Company agreed not to sell acquired properties in non-exempt transactions for periods up to 15 years from the date of the TRC acquisition as follows at December 31, 2013: One Rodney Square and 130/150/170 Radnor Financial Center (January, 2015); and One Logan Square, Two Logan Square and Radnor Corporate Center (January, 2020). In the Prentiss acquisition, the Company assumed the obligation of Prentiss not to sell Concord Airport Plaza before March, 2018. The Company’s agreements generally provide that it may dispose of the subject properties only in transactions that qualify as tax-free exchanges under Section 1031 of the Internal Revenue Code or in other tax deferred transactions. If the Company were to sell a restricted property before expiration of the restricted period in a non-exempt transaction, the Company may be required to make significant payments to the parties who sold the applicable property on account of tax liabilities attributed to them. Similarly, as part of our 2013 acquisition of substantially all of the equity interests in the partnerships that own One and Two Commerce Square, we agreed, for the benefit of affiliates of the holder of the 1% residual ownership interest in these properties, to not sell these two properties in certain taxable transactions prior to October 20, 2013 without the holder’s consent.

As part of the Company’s acquisition of properties from time to time in tax-deferred transactions, the Company has agreed to provide certain of the prior owners of the acquired properties with the right to guarantee the Company’s indebtedness. If the Company were to seek to repay the indebtedness guaranteed by the prior owner before the expiration of the applicable agreement, the Company would be required to provide the prior owner an opportunity to guaranty qualifying replacement debt. These debt maintenance agreements may limit the Company’s ability to refinance indebtedness on terms favorable to the Company. As part of our 2013 acquisition of substantially all of the equity interests in the partnerships that own One and Two Commerce Square, we agreed, for the benefit of affiliates of the holder of the 1% residual ownership interest in these properties, to maintain qualifying mortgage debt through October 20, 2021, in the amounts of not less than $130.0 million on One Commerce Square and $107.9 million on Two Commerce Square. Similarly, we have agreements in place with other contributors of assets to us that obligate us to maintain debt available for then to guaranty.

During 2008, in connection with the development of the IRS Philadelphia Campus and the Cira South Garage, the Company entered into a historic tax credit and a new market tax credit arrangement, respectively. The Company is required to be in compliance with various laws, regulations and contractual provisions that apply to its historic and new market tax credit arrangements. Non-compliance with applicable requirements could result in projected tax benefits not being realized and require a refund to USB or reduction of investor capital contributions, which are reported as deferred income in the Company’s consolidated balance sheet, until such time as its obligation to deliver tax benefits is relieved. The compliance periods for the tax credit arrangements run through 2015. The Company does not anticipate that any material refunds or reductions of investor capital contributions will be required in connection with these arrangements.

The Company invests in its properties and regularly incurs capital expenditures in the ordinary course to maintain the properties. The Company believes that such expenditures enhance its competitiveness. The Company also enters into construction, utility and service contracts in the ordinary course of business which may extend beyond one year. These contracts typically provide for cancellation with insignificant or no cancellation penalties.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2013
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS The Company has evaluated subsequent events through the date the financial statements were issued.

Summary of Quarterly Results

12 Months Ended

Dec. 31, 2013

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information [Text Block]

SUMMARY OF QUARTERLY RESULTS (UNAUDITED)

The following is a summary of quarterly financial information as of and for the years ended December 31, 2013 and 2012 (in thousands, except per share data):



	1st Quarter		2nd Quarter		3rd Quarter		4th Quarter (a)
2013
Total revenue	$	139,554	$	140,644	$	143,354	$	138,658
Net income (loss)	3,919		7,180		11,088		21,002
Net income (loss) allocated to Common Shares	2,058		5,308		9,173		18,975
Basic earnings (loss) per Common Share	$	0.01	$	0.03	$	0.06	$	0.12
Diluted earnings (loss) per Common Share	$	0.01	$	0.03	$	0.06	$	0.12
2012
Total revenue	$	133,516	$	131,530	$	134,238	$	136,395
Net income (loss)	9,336		6,802		17,089		(26,698		)
Net income (loss) allocated to Common Shares	7,108		1,537		13,949		(30,832		)
Basic earnings (loss) per Common Share	$	0.05	$	0.01	$	0.10	$	(0.21	)
Diluted earnings (loss) per Common Share	$	0.05	$	0.01	$	0.10	$	(0.21	)

(a) The consolidated statement of operations for the fourth quarter of 2012 also contained an out of period deferred compensation expense adjustment of $0.6 million relating to the acceleration of deferred compensation for certain of our executive personnel who reached qualifying retirement conditions that should have been expensed in prior periods (please see Note 14 for further discussion regarding the qualifying retirement conditions). This resulted in an overstatement of expense by $0.6 million in the fourth quarter of 2012, and an understatement of expense by $0.2 million, $0.3 million, and a nominal amount in the third, second, and first quarters of 2012, respectively, and $0.1 million in the year-ended December 31, 2011. As management believes that this error was not material to prior years' consolidated financial statements and that the impact of recording the error in the current year is not material to the Company's consolidated financial statements, the Company recorded the related adjustment in the current year.

The summation of quarterly earnings per share amounts do not necessarily equal the full year amounts due to rounding. The above information was updated to reclassify amounts previously reported to reflect discontinued operations. See Note 2 and Note 10.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2013

Valuation and Qualifying Accounts Disclosure [Line Items]

Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]

Brandywine Realty Trust and Brandywine Operating Partnership, L.P.

Schedule II

Valuation and Qualifying Accounts

(in thousands)



Description	Balance at Beginning of Year		Additions		Deductions (1)		Balance at End of Year
Allowance for doubtful accounts:
Year-ended December 31, 2013	$	16,646	$	1,384	$	1,782	$	16,248
Year-ended December 31, 2012	$	15,485	$	1,891	$	730	$	16,646
Year-ended December 31, 2011	$	15,222	$	928	$	665	$	15,485


(1)	Deductions represent amounts that the Company had fully reserved for in prior years and pursuit of collection of such amounts was ceased during the year.

Schedule III - Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2013

SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]

Real Estate and Accumulated Depreciation Disclosure [Text Block]



								Gross Amount at Which Carried
				Initial Cost				December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013 (a)	Land	Building and Improvements	Net Improvements (Retirements) Since Acquisition		Land	Building and Improvements	Total (b)	Accumulated Depreciation at December 31, 2013 (c)	Year of Construction	Year Acquired	Depreciable Life
PENNSYLVANIA SUBURBS
400 Berwyn Park	Berwyn	PA	—	2,657	4,462	13,711		2,657	18,172	20,829	5,478	1999	1999	40
300 Berwyn Park	Berwyn	PA	—	2,206	13,422	4,176		2,206	17,598	19,804	8,004	1989	1997	40
1050 Westlakes Drive	Berwyn	PA	—	2,611	10,445	5,046		2,611	15,490	18,101	7,264	1984	1999	40
1200 Swedesford Road	Berwyn	PA	—	2,595	11,809	3,533		2,595	15,341	17,936	5,464	1994	2001	40
200 Berwyn Park	Berwyn	PA	—	1,533	9,460	2,255		1,533	11,714	13,247	5,246	1987	1997	40
1180 Swedesford Road	Berwyn	PA	—	2,086	8,342	2,628		2,086	10,969	13,055	3,113	1987	2001	40
100 Berwyn Park	Berwyn	PA	—	1,180	7,290	2,173		1,180	9,462	10,642	4,241	1986	1997	40
1160 Swedesford Road	Berwyn	PA	—	1,781	7,124	1,412		2,088	8,228	10,316	2,491	1986	2001	40
1100 Cassett Road	Berwyn	PA	—	1,695	6,779	1,267		1,695	8,046	9,741	2,275	1997	2001	40
980 Harvest Drive	Blue Bell	PA	—	3,304	16,960	(110	)	3,303	16,850	20,153	6,542	1988	2002	40
925 Harvest Drive	Blue Bell	PA	—	1,671	6,606	759		1,671	7,364	9,035	3,265	1990	1998	40
920 Harvest Drive	Blue Bell	PA	—	1,209	6,595	(528	)	1,209	6,068	7,277	2,898	1990	1998	40
181 Washington Street	Conshohocken	PA	—	6,927	14,722	634		6,927	15,357	22,284	217	1999	2013	40
426 Lancaster Avenue	Devon	PA	—	1,689	6,756	395		1,689	7,152	8,841	3,259	1990	1998	40
52 Swedesford Square	East Whiteland Twp.	PA	—	4,241	16,579	2,630		4,241	19,209	23,450	7,560	1988	1998	40
One Progress Drive	Horsham	PA	—	1,399	5,629	5,214		1,399	10,843	12,242	3,818	1986	1996	40
500 Enterprise Drive	Horsham	PA	—	1,303	5,188	3,228		1,303	8,416	9,719	3,577	1990	1996	40
640 Freedom Business Center	King Of Prussia	PA	—	4,222	16,891	3,450		4,222	20,341	24,563	8,747	1991	1998	40
555 Croton Road	King of Prussia	PA	—	4,486	17,943	1,330		4,486	19,273	23,759	6,143	1999	2001	40
630 Allendale Road	King of Prussia	PA	—	2,836	4,028	12,223		2,636	16,450	19,086	5,264	2000	2000	40
620 Freedom Business Center	King Of Prussia	PA	—	2,770	11,014	3,755		2,770	14,770	17,540	7,286	1986	1998	40
1000 First Avenue	King Of Prussia	PA	—	2,772	10,936	2,787		2,772	13,723	16,495	5,949	1980	1998	40
1060 First Avenue	King Of Prussia	PA	—	2,712	10,953	2,728		2,712	13,681	16,393	6,016	1987	1998	40
630 Freedom Business Center	King Of Prussia	PA	—	2,773	11,144	1,971		2,773	13,115	15,888	5,856	1989	1998	40
1020 First Avenue	King Of Prussia	PA	—	2,168	8,576	4,522		2,168	13,098	15,266	5,999	1984	1998	40
1040 First Avenue	King Of Prussia	PA	—	2,860	11,282	586		2,860	11,868	14,728	4,859	1985	1998	40
610 Freedom Business Center	King Of Prussia	PA	—	2,017	8,070	2,369		2,017	10,440	12,457	4,388	1985	1998	40
650 Park Avenue	King Of Prussia	PA	—	1,916	4,378	1,771		1,916	6,149	8,065	2,722	1968	1998	40
500 North Gulph Road	King Of Prussia	PA	—	1,303	5,201	1,548		1,303	6,749	8,052	3,151	1979	1996	40
741 First Avenue	King Of Prussia	PA	—	1,287	5,151	11		1,287	5,162	6,449	2,242	1966	1998	40
751-761 Fifth Avenue	King Of Prussia	PA	—	1,097	4,391	31		1,097	4,422	5,519	1,917	1967	1998	40
620 Allendale Road	King Of Prussia	PA	—	1,020	3,839	654		1,020	4,493	5,513	1,869	1961	1998	40
600 Park Avenue	King Of Prussia	PA	—	1,012	4,048	385		1,012	4,433	5,445	1,925	1964	1998	40



								Gross Amount at Which Carried
				Initial Cost				December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013 (a)	Land	Building and Improvements	Net Improvements (Retirements) Since Acquisition		Land	Building and Improvements	Total (b)	Accumulated Depreciation at December 31, 2013 (c)	Year of Construction	Year Acquired	Depreciable Life
660 Allendale Road	King Of Prussia	PA	—	396	948	2,957		1,085	3,216	4,301	623	2011	1998	40
640 Allendale Road	King of Prussia	PA	—	439	432	1,579		439	2,012	2,451	722	2000	2000	40
101 Lindenwood Drive	Malvern	PA	—	4,152	16,606	3,722		4,152	20,329	24,481	6,569	1988	2001	40
301 Lindenwood Drive	Malvern	PA	—	2,729	10,915	2,667		2,729	13,582	16,311	4,424	1984	2001	40
300 Lindenwood Drive	Malvern	PA	—	848	3,394	1,265		848	4,659	5,507	1,889	1991	2001	40
100 Lindenwood Drive	Malvern	PA	—	473	1,892	208		473	2,100	2,573	729	1985	2001	40
200 Lindenwood Drive	Malvern	PA	—	324	1,295	339		324	1,634	1,958	557	1984	2001	40
14 Campus Boulevard	Newtown Square	PA	—	2,244	4,217	1,515		2,244	5,733	7,977	2,984	1998	1998	40
17 Campus Boulevard	Newtown Square	PA	—	1,108	5,155	(397	)	1,108	4,758	5,866	1,519	2001	1997	40
11 Campus Boulevard	Newtown Square	PA	—	1,112	4,067	672		1,112	4,739	5,851	1,812	1998	1999	40
15 Campus Boulevard	Newtown Square	PA	—	1,164	3,896	228		1,164	4,125	5,289	1,267	2002	2000	40
18 Campus Boulevard	Newtown Square	PA	—	787	3,312	(183	)	787	3,129	3,916	1,525	1990	1996	40
401 Plymouth Road	Plymouth Meeting	PA	—	6,198	16,131	17,096		6,198	33,226	39,424	10,394	2001	2000	40
4000 Chemical Road	Plymouth Meeting	PA	—	4,373	24,546	3,292		4,373	27,838	32,211	5,628	2006	2001	40
610 West Germantown Pike	Plymouth Meeting	PA	—	3,651	14,514	3,299		3,651	17,813	21,464	5,285	1987	2002	40
600 West Germantown Pike	Plymouth Meeting	PA	—	3,652	15,288	2,064		3,652	17,352	21,004	5,119	1986	2002	40
630 West Germantown Pike	Plymouth Meeting	PA	—	3,558	14,743	1,770		3,558	16,513	20,071	5,462	1988	2002	40
620 West Germantown Pike	Plymouth Meeting	PA	—	3,572	14,435	1,607		3,572	16,042	19,614	5,140	1990	2002	40
660 West Germantown Pike(d)	Plymouth Meeting	PA	—	—	—	17,488		—	17,488	17,488	688	1987	2012	30
2240/2250 Butler Pike	Plymouth Meeting	PA	—	1,104	4,627	1,333		1,104	5,960	7,064	3,324	1984	1996	40
2260 Butler Pike	Plymouth Meeting	PA	—	661	2,727	1,242		661	3,969	4,630	2,052	1984	1996	40
120 West Germantown Pike	Plymouth Meeting	PA	—	685	2,773	961		685	3,735	4,420	1,812	1984	1996	40
140 West Germantown Pike	Plymouth Meeting	PA	—	481	1,976	160		481	2,135	2,616	1,017	1984	1996	40
351 Plymouth Road	Plymouth Meeting	PA	—	1,043	555	—		1,043	555	1,598	121	N/A	2000	40
150 Radnor Chester Road	Radnor	PA	—	11,925	36,986	11,799		11,896	48,813	60,709	15,790	1983	2004	29
One Radnor Corporate Center	Radnor	PA	—	7,323	28,613	22,975		7,322	51,588	58,910	15,805	1998	2004	29
201 King of Prussia Road	Radnor	PA	—	8,956	29,811	5,214		8,948	35,032	43,980	13,938	2001	2004	25



555 Lancaster Avenue	Radnor	PA	—	8,014	16,508	18,993	8,609	34,906	43,515	12,970	1973	2004	24
Four Radnor Corporate Center	Radnor	PA	—	5,406	21,390	11,967	5,705	33,058	38,763	12,752	1995	2004	30
Five Radnor Corporate Center	Radnor	PA	—	6,506	25,525	5,124	6,578	30,577	37,155	6,918	1998	2004	38
Three Radnor Corporate Center	Radnor	PA	—	4,773	17,961	2,715	4,791	20,658	25,449	7,226	1998	2004	29
Two Radnor Corporate Center	Radnor	PA	—	3,937	15,484	3,872	3,942	19,350	23,292	6,031	1998	2004	29
130 Radnor Chester Road	Radnor	PA	—	2,573	8,338	3,491	2,567	11,834	14,401	3,825	1983	2004	25
170 Radnor Chester Road	Radnor	PA	—	2,514	8,147	1,678	2,509	9,831	12,340	3,316	1983	2004	25
200 Radnor Chester Road (d)	Radnor	PA	—	—	—	842	—	842	842	—	N/A	2005	N/A



								Gross Amount at Which Carried
				Initial Cost				December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013 (a)	Land	Building and Improvements	Net Improvements (Retirements) Since Acquisition		Land	Building and Improvements	Total (b)	Accumulated Depreciation at December 31, 2013 (c)	Year of Construction	Year Acquired	Depreciable Life
101 West Elm Street	W. Conshohocken	PA	—	6,251	25,209	2,784		6,251	27,992	34,243	6,556	1999	2005	40
1 West Elm Street	W. Conshohocken	PA	—	3,557	14,249	1,115		3,557	15,364	18,921	3,626	1999	2005	40
595 East Swedesford Road	Wayne	PA	—	2,729	10,917	2,307		2,729	13,225	15,954	3,946	1998	2003	40
575 East Swedesford Road	Wayne	PA	—	2,178	8,712	1,681		2,178	10,393	12,571	3,255	1985	2003	40
565 East Swedesford Road	Wayne	PA	—	1,872	7,489	1,820		1,872	9,309	11,181	2,840	1984	2003	40
585 East Swedesford Road	Wayne	PA	—	1,350	5,401	116		1,350	5,517	6,867	1,397	1998	2003	40
PHILADELPHIA CBD
2970 Market Street	Philadelphia	PA	190,964	22,430	217,763	10,591		22,430	228,354	250,784	21,169	2010	2007	40
2929 Arch Street	Philadelphia	PA	—	—	208,570	29,291		12,482	225,380	237,862	74,828	2005	N/A	40
1717 Arch Street	Philadelphia	PA	—	—	98,188	52,953		25,195	125,946	151,141	12,294	1990	2010	40
2001 Market Street	Philadelphia	PA	112,000	15,323	120,842	(642	)	15,323	120,200	135,523	107	1992	2013	40
130 North 18th Street	Philadelphia	PA	—	14,496	107,736	11,782		14,473	119,541	134,014	37,538	1998	2004	34
100 North 18th Street	Philadelphia	PA	88,583	16,066	100,255	6,038		16,066	106,293	122,359	32,227	1988	2004	36
2005 Market Street	Philadelphia	PA	125,089	15,161	122,486	(17,465	)	15,161	105,021	120,182	94	1987	2013	40
2930 Chestnut Street	Philadelphia	PA	40,101	—	76,008	2,586		—	78,594	78,594	6,606	2010	N/A	40
1900 Market Street	Philadelphia	PA	—	7,768	17,263	64		7,768	17,327	25,095	629	1981	2012	30
3020 Market Street	Philadelphia	PA	—	—	21,417	3,010		—	24,427	24,427	2,144	1959	2011	26
101 - 103 Juniper Street	Philadelphia	PA	—	—	14,401	324		478	14,247	14,725	1,340	2010	2006	40
Philadelphia Marine Center	Philadelphia	PA	—	532	2,196	3,196		628	5,296	5,924	2,186	Various	1998	40
METROPOLITAN WASHINGTON, D.C.
11720 Beltsville Drive	Beltsville	MD	—	3,831	16,661	3,982		3,903	20,571	24,474	5,743	1987	2006	46
11700 Beltsville Drive	Beltsville	MD	—	2,808	12,081	292		2,863	12,319	15,182	2,415	1981	2006	46
11710 Beltsville Drive	Beltsville	MD	—	2,278	11,100	(814	)	2,321	10,243	12,564	2,096	1987	2006	46
6600 Rockledge Drive	Bethesda	MD	—	—	37,421	11,538		—	48,960	48,960	12,867	1981	2006	50
11740 Beltsville Drive	Bethesda	MD	—	198	870	42		202	908	1,110	189	1987	2006	46
12015 Lee Jackson Memorial Highway	Fairfax	VA	—	3,770	22,895	3,665		3,842	26,489	30,331	6,016	1985	2006	42
11781 Lee Jackson Memorial Highway	Fairfax	VA	—	3,246	19,836	24		3,307	19,800	23,107	4,092	1982	2006	40
4401 Fair Lakes Court	Fairfax	VA	—	1,569	11,982	237		1,599	12,190	13,789	2,202	1988	2006	52
3141 Fairview Park Drive (e)	Falls Church	VA	21,630	5,918	40,981	11,545		7,081	51,365	58,446	9,049	1988	2006	51
2340 Dulles Corner Boulevard	Herndon	VA	—	16,345	65,379	18,280		16,129	83,875	100,004	24,559	1987	2006	40
2291 Wood Oak Drive	Herndon	VA	—	8,243	52,413	13,499		8,782	65,373	74,155	11,311	1999	2006	55
196/198 Van Buren Street	Herndon	VA	—	7,931	43,812	8,709		8,348	52,104	60,452	8,594	1991	2006	53
2251 Corporate Park Drive	Herndon	VA	—	11,472	45,893	2,055		11,472	47,948	59,420	8,434	2000	2006	40
2355 Dulles Corner Boulevard	Herndon	VA	—	10,365	43,876	4,528		10,365	48,405	58,770	10,863	1988	2006	40
2411 Dulles Corner Park	Herndon	VA	—	7,279	46,340	3,508		7,417	49,710	57,127	10,475	1990	2006	50
13880 Dulles Corner Lane	Herndon	VA	—	7,236	39,213	2,498		7,373	41,574	48,947	6,634	1997	2006	55



							Gross Amount at Which Carried
				Initial Cost			December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013 (a)	Land	Building and Improvements	Net Improvements (Retirements) Since Acquisition	Land	Building and Improvements	Total (b)	Accumulated Depreciation at December 31, 2013 (c)	Year of Construction	Year Acquired	Depreciable Life
2121 Cooperative Way	Herndon	VA	—	5,598	38,639	2,292	5,795	40,734	46,529	6,598	2000	2006	54
2201 Cooperative Way	Herndon	VA	—	4,809	34,093	2,349	4,809	36,442	41,251	5,921	1990	2006	54
13825 Sunrise Valley Drive	Herndon	VA	—	3,794	19,365	1,032	3,866	20,326	24,192	3,521	1989	2006	46
1676 International Drive	Mclean	VA	59,698	18,437	97,538	2,501	18,785	99,691	118,476	17,693	1999	2006	55
8260 Greensboro Drive	Mclean	VA	31,697	7,952	33,964	1,794	8,102	35,608	43,710	6,461	1980	2006	52
1880 Campus Commons Drive	Reston	VA	—	6,164	28,114	6,315	6,281	34,312	40,593	5,754	1985	2006	52
2273 Research Boulevard	Rockville	MD	—	5,167	31,110	3,589	5,237	34,628	39,865	8,658	1999	2006	45
2275 Research Boulevard	Rockville	MD	—	5,059	29,668	2,964	5,154	32,537	37,691	6,474	1990	2006	45
2277 Research Boulevard	Rockville	MD	—	4,649	26,952	695	4,733	27,563	32,296	5,014	1986	2006	45
1900 Gallows Road	Vienna	VA	—	7,797	47,817	9,619	7,944	57,288	65,232	9,483	1989	2006	52
8521 Leesburg Pike	Vienna	VA	—	4,316	30,885	3,198	4,397	34,002	38,399	5,192	1984	2006	51
NEW JERSEY/DELAWARE
457 Haddonfield Road	Cherry Hill	NJ	—	2,142	9,120	1,334	2,142	10,454	12,596	4,884	1990	1996	40
200 Lake Drive East	Cherry Hill	NJ	—	2,069	8,275	1,299	2,069	9,573	11,642	3,264	1989	2001	40
220 Lake Drive East	Cherry Hill	NJ	—	2,144	8,798	646	2,144	9,443	11,587	3,152	1988	2001	40
210 Lake Drive East	Cherry Hill	NJ	—	1,645	6,579	1,110	1,645	7,689	9,334	2,509	1986	2001	40
20 East Clementon Road	Gibbsboro	NJ	—	769	3,055	530	769	3,585	4,354	1,574	1986	1997	40
10 Foster Avenue	Gibbsboro	NJ	—	244	971	78	244	1,049	1,293	470	1983	1997	40
7 Foster Avenue	Gibbsboro	NJ	—	231	921	123	231	1,044	1,275	435	1983	1997	40
50 East Clementon Road	Gibbsboro	NJ	—	114	964	3	114	967	1,081	428	1986	1997	40
2 Foster Avenue	Gibbsboro	NJ	—	185	730	16	185	746	931	333	1974	1997	40
4 Foster Avenue	Gibbsboro	NJ	—	183	726	5	183	732	915	324	1974	1997	40
1 Foster Avenue	Gibbsboro	NJ	—	93	364	76	93	440	533	219	1972	1997	40
5 U.S. Avenue	Gibbsboro	NJ	—	21	81	3	21	84	105	37	1987	1997	40
5 Foster Avenue	Gibbsboro	NJ	—	9	32	26	9	58	67	27	1968	1997	40



1120 Executive Boulevard	Marlton	NJ	—	2,074	8,415	2,061	2,074	10,475	12,549	4,687	1987	1997	40
Two Eves Drive	Marlton	NJ	—	818	3,461	341	818	3,802	4,620	1,795	1987	1997	40
Five Eves Drive	Marlton	NJ	—	703	2,819	532	703	3,351	4,054	1,519	1986	1997	40
Four B Eves Drive	Marlton	NJ	—	588	2,369	420	588	2,789	3,377	1,328	1987	1997	40
Four A Eves Drive	Marlton	NJ	—	539	2,168	123	539	2,291	2,830	1,050	1987	1997	40
308 Harper Drive	Moorestown	NJ	—	1,643	6,663	929	1,643	7,592	9,235	3,155	1976	1998	40
10000 Midlantic Drive	Mt. Laurel	NJ	—	3,206	12,857	4,335	3,206	17,192	20,398	7,087	1990	1997	40
700 East Gate Drive	Mt. Laurel	NJ	—	3,569	14,436	2,094	3,569	16,530	20,099	7,269	1984	1998	40
15000 Midlantic Drive	Mt. Laurel	NJ	—	3,061	12,254	1,600	3,061	13,854	16,915	6,211	1991	1997	40
1000 Howard Boulevard	Mt. Laurel	NJ	—	2,297	9,288	3,922	2,297	13,210	15,507	5,277	1988	1997	40
1000 Atrium Way	Mt. Laurel	NJ	—	2,061	8,180	4,867	2,061	13,047	15,108	5,896	1989	1997	40



								Gross Amount at Which Carried
				Initial Cost				December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013 (a)	Land	Building and Improvements	Net Improvements (Retirements) Since Acquisition		Land	Building and Improvements	Total (b)	Accumulated Depreciation at December 31, 2013(c)	Year of Construction	Year Acquired	Depreciable Life
2000 Midlantic Drive	Mt. Laurel	NJ	—	2,202	8,823	2,490		2,202	11,313	13,515	4,752	1989	1997	40
701 East Gate Drive	Mt. Laurel	NJ	—	1,736	6,877	1,780		1,736	8,657	10,393	3,452	1986	1998	40
9000 Midlantic Drive	Mt. Laurel	NJ	—	1,472	5,895	1,880		1,472	7,776	9,248	3,142	1989	1997	40
307 Fellowship Drive	Mt. Laurel	NJ	—	1,565	6,342	1,292		1,565	7,634	9,199	3,189	1981	1998	40
305 Fellowship Drive	Mt. Laurel	NJ	—	1,421	5,768	1,611		1,421	7,378	8,799	2,831	1980	1998	40
303 Fellowship Drive	Mt. Laurel	NJ	—	1,493	6,055	851		1,493	6,907	8,400	2,902	1979	1998	40
309 Fellowship Drive	Mt. Laurel	NJ	—	1,518	6,154	644		1,518	6,798	8,316	2,927	1982	1998	40
1000 Bishops Gate	Mt. Laurel	NJ	—	934	6,287	412		934	6,700	7,634	2,350	2005	2000	40
161 Gaither Drive	Mt. Laurel	NJ	—	1,016	4,064	679		1,016	4,743	5,759	1,719	1987	2001	40
815 East Gate Drive	Mt. Laurel	NJ	—	636	2,584	708		636	3,292	3,928	1,353	1986	1998	40
4000 Midlantic Drive	Mt. Laurel	NJ	—	714	5,085	(1,982	)	714	3,103	3,817	1,455	1998	1997	40
817 East Gate Drive	Mt. Laurel	NJ	—	611	2,426	152		611	2,578	3,189	1,088	1986	1998	40
400 Commerce Drive	Newark	DE	—	2,528	9,220	1,048		2,528	10,268	12,796	3,627	1997	2002	40
100 Commerce Drive	Newark	DE	—	1,160	4,633	857		1,160	5,490	6,650	2,381	1989	1997	40
200 Commerce Drive	Newark	DE	—	911	4,414	1,018		911	5,432	6,343	2,012	1998	2002	40
Main Street - Plaza 1000	Voorhees	NJ	—	2,732	10,942	3,074		2,732	14,016	16,748	9,611	1988	1997	40
Main Street - Piazza	Voorhees	NJ	—	696	2,802	2,529		696	5,332	6,028	1,415	1990	1997	40
Main Street - Promenade	Voorhees	NJ	—	531	2,052	445		531	2,496	3,027	1,097	1988	1997	40
920 North King Street	Wilmington	DE	—	6,141	21,140	2,485		6,141	23,625	29,766	6,854	1989	2004	30
300 Delaware Avenue	Wilmington	DE	—	6,368	13,739	2,546		6,368	16,285	22,653	5,836	1989	2004	23
Two Righter Parkway	Wilmington	DE	—	2,802	11,217	6,264		2,802	17,481	20,283	4,069	1987	2001	40
One Righter Parkway	Wilmington	DE	—	2,545	10,195	5,088		2,545	15,282	17,827	7,982	1989	1996	40
RICHMOND
4364 South Alston Avenue	Durham	NC	—	1,622	6,419	1,031		1,580	7,491	9,071	3,010	1985	1998	40
4805 Lake Brooke Drive	Glen Allen	VA	—	1,640	6,567	1,136		1,640	7,703	9,343	2,953	1996	1998	40
Overlook I	Glen Allen	VA	—	748	3,976	600		790	4,533	5,323	439	1998	2011	40
Overlook II	Glen Allen	VA	—	748	4,492	77		790	4,526	5,316	475	2000	2011	40
2812 Emerywood Parkway	Henrico	VA	—	1,069	4,281	505		1,069	4,786	5,855	2,017	1980	1998	40
300 Arboretum Place	Richmond	VA	—	5,450	21,892	3,457		5,450	25,349	30,799	10,047	1988	1998	40
7501 Boulders View Drive	Richmond	VA	—	4,669	19,699	2,112		4,925	21,555	26,480	4,030	1989	2007	40
7300 Beaufont Springs Drive	Richmond	VA	—	4,672	19,689	1,906		4,922	21,345	26,267	3,534	2000	2007	40
6800 Paragon Place	Richmond	VA	—	4,552	18,414	2,020		4,552	20,434	24,986	4,057	1987	2006	40
6802 Paragon Place	Richmond	VA	—	2,917	11,454	2,912		2,917	14,366	17,283	4,666	1989	2002	40
1025 Boulders Parkway	Richmond	VA	—	2,574	11,297	1,573		2,824	12,620	15,444	2,100	1994	2007	40
2100-2116 West Laburnam Avenue	Richmond	VA	—	2,482	8,846	2,707		2,482	11,553	14,035	4,917	1984	1998	40
7401 Beaufont Springs Drive	Richmond	VA	—	2,349	10,396	992		2,599	11,138	13,737	1,904	1998	2007	40
7325 Beaufont Springs Drive	Richmond	VA	—	2,344	10,377	503		2,594	10,629	13,223	1,753	1999	2007	40



								Gross Amount at Which Carried
				Initial Cost				December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013(a)	Land	Building and Improvements	Net Improvements (Retirements) Since Acquisition		Land	Building and Improvements	Total (b)	Accumulated Depreciation at December 31, 2013 (c)	Year of Construction	Year Acquired	Depreciable Life
9011 Arboretum Parkway	Richmond	VA	—	1,857	7,702	906		1,857	8,609	10,466	3,571	1991	1998	40
6806 Paragon Place	Richmond	VA	—	—	10,288	(105	)	403	9,780	10,183	2,297	2007	2005	40
9100 Arboretum Parkway	Richmond	VA	—	1,362	5,489	761		1,362	6,250	7,612	2,591	1987	1998	40
2511 Brittons Hill Road	Richmond	VA	—	1,202	4,820	1,221		1,202	6,041	7,243	2,652	1987	1998	40
100 Gateway Centre Parkway	Richmond	VA	—	391	5,410	616		391	6,027	6,418	1,725	2001	1998	40
9200 Arboretum Parkway	Richmond	VA	—	985	3,973	1,225		985	5,198	6,183	2,136	1987	1998	40
9210 Arboretum Parkway	Richmond	VA	—	1,110	4,474	527		1,110	5,001	6,111	2,151	1988	1998	40
2201-2245 Tomlynn Street	Richmond	VA	—	1,020	4,067	793		1,020	4,860	5,880	1,944	1989	1998	40
9211 Arboretum Parkway	Richmond	VA	—	582	2,433	886		582	3,320	3,902	1,206	1991	1998	40
2221-2245 Dabney Road	Richmond	VA	—	530	2,123	349		530	2,472	3,002	889	1994	1998	40
2212-2224 Tomlynn Street	Richmond	VA	—	502	2,014	395		502	2,409	2,911	938	1985	1998	40
2244 Dabney Road	Richmond	VA	—	550	2,203	37		550	2,240	2,790	947	1993	1998	40
2277 Dabney Road	Richmond	VA	—	507	2,034	241		507	2,274	2,781	889	1986	1998	40
2248 Dabney Road	Richmond	VA	—	512	2,049	131		512	2,181	2,693	898	1989	1998	40
2161-2179 Tomlynn Street	Richmond	VA	—	423	1,695	315		423	2,010	2,433	764	1985	1998	40
2246 Dabney Road	Richmond	VA	—	455	1,822	18		455	1,840	2,295	770	1987	1998	40
2251 Dabney Road	Richmond	VA	—	387	1,552	110		387	1,662	2,049	703	1983	1998	40
2256 Dabney Road	Richmond	VA	—	356	1,427	235		356	1,662	2,018	746	1982	1998	40
2130-2146 Tomlynn Street	Richmond	VA	—	353	1,416	169		353	1,585	1,938	636	1988	1998	40
2120 Tomlynn Street	Richmond	VA	—	281	1,125	179		281	1,304	1,585	560	1984	1998	40
2240 Dabney Road	Richmond	VA	—	264	1,059	98		264	1,157	1,421	451	1984	1998	40
Boulders Land	Richmond	VA	—	1,256	—	28		1,259	25	1,284	—	N/A	2007	N/A



											Gross Amount at Which Carried
					Initial Cost						December 31, 2013
Property Name	City	State	Encumberances at December 31, 2013 (a)		Land		Building and Improvements		Net Improvements (Retirements) Since Acquisition		Land		Building and Improvements		Total (b)		Accumulated Depreciation at December 31, 2013 (c)		Year of Construction	Year Acquired	Depreciable Life
AUSTIN
11305 Four Points Drive	Austin	TX	—		962		35,894		36,856		962		35,894		36,856		—		2008	2013	40
CALIFORNIA
5900 & 5950 La Place Court	Carlsbad	CA	—		3,706		11,185		3,401		3,955		14,337		18,292		3,015		1988	2006	48
5963 La Place Court	Carlsbad	CA	—		2,824		9,413		2,197		2,999		11,435		14,434		2,164		1987	2006	55
2035 Corte Del Nogal	Carlsbad	CA	—		3,261		6,077		1,175		3,499		7,015		10,514		1,902		1991	2006	39
1200 Concord Avenue	Concord	CA	—		6,395		24,664		809		6,515		25,352		31,867		6,693		1984	2006	34
1220 Concord Avenue	Concord	CA	—		6,476		24,966		260		6,476		25,226		31,702		6,375		1984	2006	34
155 Grand Avenue	Oakland	CA	—		13,556		54,267		5,764		13,557		60,031		73,588		11,951		1990	2007	40
Two Kaiser Plaza	Oakland	CA	—		7,841		—		—		7,841		—		7,841		—		N/A	2006	N/A
Oakland Lot B	Oakland	CA	—		4,342		—		—		4,342		—		4,342		—		N/A	2006	N/A
	Total:		$	669,762	$	634,189	$	3,454,900	$	617,057	$	680,513	$	3,988,776	$	4,669,289	$	983,808


(a)	Excludes the effect of any net interest premium/(discount).


(b)	Reconciliation of Real Estate:

The following table reconciles the real estate investments from January 1, 2011 to December 31, 2013 (in thousands):



	2013			2012			2011
Balance at beginning of year	$	4,726,169		$	4,793,080		$	4,834,111
Additions:
Acquisitions	347,510			50,579			31,454
Capital expenditures and assets placed into service	109,740			90,619			133,550
Less:
Dispositions	(474,275		)	(168,408		)	(163,971		)
Retirements	(39,855		)	(39,701		)	(42,064		)
Balance at end of year	$	4,669,289		$	4,726,169		$	4,793,080

The aggregate cost for federal income tax purposes is $4.0 billion as of December 31, 2013.


(c)	Reconciliation of Accumulated Depreciation:

The following table reconciles the accumulated depreciation on real estate investments from January 1, 2011 to December 31, 2013 (in thousands):



	2013			2012			2011
Balance at beginning of year	$	954,665		$	865,710		$	776,078
Additions:
Depreciation expense — continuing operations	150,236			154,095			157,691
Depreciation expense — discontinued operations	9,164			2,143			1,185
Less:
Dispositions	(91,890		)	(28,270		)	(62,022		)
Retirements	$	(38,367	)	$	(39,013	)	$	(7,222	)
Balance at end of year	$	983,808		$	954,665		$	865,710

(d) Total net improvements since acquisition for these development properties do not include amounts allocated to construction-in-progress, as shown within the Company's consolidated balance sheet as of December 31, 2013.

(e) This property was contributed to an unconsolidated real estate venture, however, the Company will continue to consolidate this property due to its continuing involvement in this property resulting from its ongoing lease at this property and its 50% ownership interest in the venture. Please see Note 3 to the consolidated financial statements for additional information.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Reclassifications

Principles of Consolidation

Use of Estimates

Operating Properties

Purchase Price Allocation

Depreciation and Amortization [Policy Text Block]

Depreciation and Amortization

Construction in Progress



	December 31,
	2013		2012		2011
Development	$	156	$	57	$	—
Redevelopment	194		353		—
Tenant Improvements	3,323		4,259		4,034
Total	$	3,673	$	4,669	$	4,034

Impairment or Disposal of Long-Lived Assets

The Company determined during its impairment review of the year-ended December 31, 2013, 2012 and 2011, that no impairment charges were necessary.

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

Restricted Cash, Policy [Policy Text Block]

Restricted Cash

Restricted cash consists of cash held as collateral to provide credit enhancement for the Company’s mortgage debt, cash for property taxes, capital expenditures and tenant improvements.

Accounts receivable and accrued rent receivable policy [Policy Text Block]

Accounts Receivable and Accrued Rent Receivable

Investments in Unconsolidated Real Estate Ventures

Deferred Costs, Policy [Policy Text Block]

Deferred Costs

Notes Receivable

Revenue Recognition

The Company derives parking revenues from leases, monthly parking and transient parking. The Company recognizes parking revenue as earned.

The Company receives management and development fees from third parties.

No tenant represented greater than 10% of the Company’s rental revenue in 2013, 2012 or 2011

Income Taxes

Parent Company

The tax basis of the Parent Company’s assets was $4.0 billion for each of the years ended December 31, 2013 and 2012.

Operating Partnership

The tax basis of the Operating Partnership’s assets was $4.0 billion for each of the years ended December 31, 2013 and 2012.

The Operating Partnership has elected to treat several of its subsidiaries as TRSs, which are subject to federal, state and local income tax.

Earnings Per Share, Policy [Policy Text Block]

Earnings Per Share

Earnings Per Unit

Stock-Based Compensation Plans

Comprehensive Income, Policy [Policy Text Block]

Comprehensive Income

Accounting for Derivative Instruments and Hedging Activities

Fair Value Measurements


•	Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access;

•


•	Level 3 inputs are unobservable inputs for the asset or liability, which is typically based on an entity’s own assumptions, as there is little, if any, related market activity or information.

The following table sets forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis as of December 31, 2013 (in thousands):



	Fair Value Measurements at Reporting Date Using:
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Unobservable Inputs
Description	2013		(Level 1)		(Level 2)		(Level 3)
Recurring
Assets:
Interest Rate Swaps	$	767	$	—	$	767	$	—
Liabilities:
Interest Rate Swaps	$	2,188	$	—	$	2,188	$	—

The following table sets forth the Company’s financial liabilities that were accounted for at fair value on a recurring basis as of December 31, 2012 (in thousands):



	Fair Value Measurements at Reporting Date Using:
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Unobservable Inputs
Description	2012		(Level 1)		(Level 2)		(Level 3)
Recurring
Liabilities:
Interest Rate Swaps	$	14,210	$	—	$	14,210	$	—

We classify our interest rate swaps, shown above, within Level 2 as the valuation inputs are based on quoted prices and market observable data of similar instruments.


•	Non-financial assets and liabilities initially measured at fair value in an acquisition or business combination that are not remeasured at least quarterly at fair value,


•	Long-lived assets measured at fair value due to an impairment in accordance with the accounting standard for the impairment or disposal of long-lived assets,


•	Equity and cost method investments measured at fair value due to an impairment in accordance with the accounting standard for investments,


•	Notes receivable adjusted for any impairment in its value in accordance with the accounting standard for loan receivables, and


•	Asset retirement obligations initially measured at fair value under the accounting standard for asset retirement obligations.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]



	Fair Value Measurements at Reporting Date Using:
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Unobservable Inputs
Description	2013		(Level 1)		(Level 2)		(Level 3)
Recurring
Assets:
Interest Rate Swaps	$	767	$	—	$	767	$	—
Liabilities:
Interest Rate Swaps	$	2,188	$	—	$	2,188	$	—

The following table sets forth the Company’s financial liabilities that were accounted for at fair value on a recurring basis as of December 31, 2012 (in thousands):



	Fair Value Measurements at Reporting Date Using:
	December 31,		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Unobservable Inputs
Description	2012		(Level 1)		(Level 2)		(Level 3)
Recurring
Liabilities:
Interest Rate Swaps	$	14,210	$	—	$	14,210	$	—

Schedule of Capitalized Salaries Including Bonuses and Benefits [Table Text Block]



	December 31,
	2013		2012		2011
Development	$	156	$	57	$	—
Redevelopment	194		353		—
Tenant Improvements	3,323		4,259		4,034
Total	$	3,673	$	4,669	$	4,034

Real Estate Investments (Tables)

12 Months Ended

Dec. 31, 2013

Real Estate [Abstract]

Gross carrying value of the Company's Properties



	2013		2012
Land	$	680,513	$	662,107
Building and improvements	3,504,060		3,576,065
Tenant improvements	484,716		487,997
	$	4,669,289	$	4,726,169

Schedule of Business Acquisitions, by Acquisition [Table Text Block]



	December 19, 2013
Building, land and improvements	$	255,705
Intangible assets acquired	85,036
Below market lease liabilities assumed	(8,637		)
	$	332,104

Mortgage debt assumed - at fair value (1)	(238,082		)
Return of existing equity method investment	(30,424		)
Net working capital assumed	10,423
Non-controlling interest	(946		)
Total cash payment at settlement	$	73,075

(1) Principal outstanding on assumed mortgage debt at December 19, 2013 was $237.1 million.

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]

Intangible assets acquired and intangible liabilities assumed consist of the following (in thousands):



	December 19, 2013			Weighted Average Amortization Period (in years)
Intangible assets:
In-place lease value	$	80,916		7.9
Above market tenant leases acquired	4,120			6.9
Total	$	85,036

Intangible liabilities:
Below market leases acquired	$	(8,637	)	6.5

Business Acquisition, Pro Forma Information [Table Text Block]



	December 31,
	2013		2012

Pro forma revenue	$	610,979	$	592,753
Pro forma income (loss) from continuing operations	21,805		(60,011		)
Pro forma net income (loss) available to common shareholders	25,957		(16,970		)

Earnings per common share from continuing operations:
Basic -- as reported	$	0.20	$	(0.36	)
Basic -- as pro forma	$	0.14	$	(0.42	)

Diluted -- as reported	$	0.20	$	(0.36	)
Diluted -- as pro forma	$	0.14	$	(0.42	)

Earnings per common share:
Basic -- as reported	$	0.23	$	(0.06	)
Basic -- as pro forma	$	0.17	$	(0.12	)

Diluted -- as reported	$	0.23	$	(0.06	)
Diluted -- as pro forma	$	0.17	$	(0.12	)

Investment in Unconsolidated Ventures (Tables)

12 Months Ended

Dec. 31, 2013

Equity Method Investments and Joint Ventures [Abstract]

Schedule of Equity Method Investments [Table Text Block]



	Ownership Percentage (a)		Carrying Amount			Company’s Share of 2013 Real Estate Venture Income (Loss)			Real Estate Venture Debt at 100%		Current Interest Rate		Debt Maturity
Broadmoor Austin Associates (f)	50	%	$	65,867		$	(52	)	$	56,616	7.04	%	Apr-23
Brandywine-AI Venture LLC	50	%	46,406			130			134,500		3.92	%	(b)
DRA (G&I) Austin (f)	50	%	17,262			(434		)	230,600		3.39	%	(c)
HSRE-Campus Crest IX, LLC (f)	30	%	13,761			—			966		L+2.20%		Jul-16
4040 Wilson LLC	50	%	13,499			—			—		N/A		N/A
TB-BDN Plymouth Apartments	50	%	12,402			5			—		L+1.70%		Dec-17
Brandywine 1919 Ventures	50	%	6,214			—			—		N/A		N/A
1000 Chesterbrook Blvd.	50	%	2,064			461			24,861		4.75	%	Dec-21
Four Tower Bridge	65	%	1,617			320			10,535		5.20	%	Feb-21
PJP VII	25	%	783			239			6,250		L+2.65%		Dec-19
Residence Inn Tower Bridge	50	%	742			326			13,700		5.63	%	Feb-16
Seven Tower Bridge	20	%	447			—			11,035		4.22	%	(d)
PJP II	30	%	330			(87		)	3,765		6.12	%	Nov-23
PJP V	25	%	175			158			5,437		6.47	%	Aug-19
PJP VI	25	%	112			70			8,404		6.08	%	Apr-23
BDN Beacon Venture LLC (i)	20	%	—			907			—		N/A		N/A
Six Tower Bridge (g)	63	%	—			165			—		N/A		N/A
One Commerce Square (h)	25	%	—			933			—		N/A		N/A
Two Commerce Square (h)	25	%	—			614			—		N/A		N/A
G&I Interchange Office LLC (DRA — N. PA) (e) (f)	20	%	—			(619		)	177,207		5.78	%	Jan-15
Two Tower Bridge (i)	35	%	—			265			—		N/A		N/A
Coppell Associates	50	%	(1,169		)	(78		)	15,984		5.75	%	Feb-16
Eight Tower Bridge (i)			—			3			—
Invesco, L.P. (i)			—			338			—
			$	180,512		$	3,664		$	699,860


(a)	Ownership percentage represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.


(b)	The debt for these properties is comprised of three fixed rate mortgages: (1) $40.0 million with a 4.40% fixed interest rate due January 1, 2019, (2) $28.0 million with a 4.65% fixed interest rate due January 1, 2022, and (3) $66.5 million with a 3.22% fixed interest rate due August 1, 2019, resulting in a time and dollar weighted average rate of 3.92%.


(c)	The debt for these properties is comprised of three mortgages: (1) $34.0 million with a 3.52% interest rate due November 1, 2018, (2) $56.0 million with a 3.19% interest rate due October 15, 2018, and (3) $140.6 million with a rate of 3.44% fixed interest rate due November 1, 2018, resulting in a time and dollar weighted average rate of 3.39%.

(d)


(e)	Proceeds received by the Company from the sale of an 80% ownership stake in the properties exceeded the historical cost of those properties. No investment in the real estate venture was reflected on the balance sheet at formation.


(f)	The basis differences associated with these ventures are allocated between cost and the underlying equity in the net assets of the investee and is accounted for as if the entity were consolidated (i.e., allocated to the Company’s relative share of assets and liabilities with an adjustment to recognize equity in earnings for the appropriate depreciation/amortization).


(g)	On June 19, 2013, we acquired ownership of Six Tower Bridge. Real estate venture income reflects our previous partnership interest for the year to date period through June 18, 2013.


(h)	On December 19, 2013, we increased our ownership interest in One and Two Commerce Square. The real estate venture income reflects our previous partnership interest for the year to date period through December 18, 2013.


(i)	The ownership interest in these properties was disposed of prior to December 31, 2013. For further information on BDN Beacon LLC, see the section entitled BDN Beacon Venture below. For further information on Two Tower Bridge, see the section entitled Two and Six Tower Bridge Exchange Transaction below.

Financial position of unconsolidated Real Estate Ventures



	December 31, 2013		December 31, 2012
Net property	$	965,475	$	923,536
Other assets	164,152		174,677
Other liabilities	49,442		53,645
Debt	699,860		724,780
Equity	380,325		319,788
Company’s share of equity (Company’s basis)	180,512		193,555

Summary of results of operations of unconsolidated Real Estate Ventures

The following is a summary of results of operations of the Real Estate Ventures in which the Company had interests as of December 31, 2013, 2012 and 2011 (in thousands):



	Years ended December 31,
	2013		2012		2011
Revenue	$	102,919	$	164,013	$	145,867
Operating expenses	40,436		70,775		63,715
Interest expense, net	26,529		41,633		42,032
Depreciation and amortization	35,138		50,241		39,172
Net income	816		1,364		948
Company’s share of income (Company’s basis)	3,664		2,741		3,775

Schedule of Maturities of Long-term Debt [Table Text Block]

As of December 31, 2013, the aggregate principal payments of recourse and non-recourse debt payable to third-parties are as follows (in thousands):



2014	$	11,940
2015	191,304
2016	42,180
2017	13,937
2018	229,780
Thereafter	210,719
	$	699,860

Deferred Costs (Tables)

12 Months Ended

Dec. 31, 2013

Deferred Costs [Abstract]

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block]

As of December 31, 2013 and 2012, the Company’s deferred costs were comprised of the following (in thousands):



	December 31, 2013
	Total Cost		Accumulated Amortization			Deferred Costs, net
Leasing Costs	$	155,885	$	(58,805	)	$	97,080
Financing Costs	40,317		(14,443		)	25,874
Total	$	196,202	$	(73,248	)	$	122,954



	December 31, 2012
	Total Cost		Accumulated Amortization			Deferred Costs, net
Leasing Costs	$	150,331	$	(58,343	)	$	91,988
Financing Costs	40,246		(9,991		)	30,255
Total	$	190,577	$	(68,334	)	$	122,243

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2013

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets



	December 31, 2013
	Total Cost		Accumulated Amortization			Intangible Assets, net
In-place lease value	$	150,782	$	(35,607	)	$	115,175
Tenant relationship value	38,692		(26,868		)	11,824
Above market leases acquired	6,673		(1,343		)	5,330
Total	$	196,147	$	(63,818	)	$	132,329
Below market leases acquired	$	81,991	$	(47,547	)	$	34,444



	December 31, 2012
	Total Cost		Accumulated Amortization			Intangible Assets, net
In-place lease value	$	87,909	$	(42,894	)	$	45,015
Tenant relationship value	56,137		(37,389		)	18,748
Above market leases acquired	8,565		(1,708		)	6,857
Total	$	152,611	$	(81,991	)	$	70,620
Below market leases acquired	$	77,083	$	(43,224	)	$	33,859

Annual amortization of intangible assets and liabilities



	Assets		Liabilities
2014	$	27,043	$	7,614
2015	23,314		5,455
2016	18,573		3,486
2017	16,573		2,890
2018	12,161		2,353
Thereafter	34,665		12,646
Total	$	132,329	$	34,444

Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Consolidated debt obligations

. DEBT OBLIGATIONS

The following table sets forth information regarding the Company’s consolidated debt obligations outstanding at December 31, 2013 and 2012 (in thousands):



Property / Location	December 31, 2013			December 31, 2012			Effective Interest Rate			Maturity Date
MORTGAGE DEBT:

Tysons Corner	$	91,395		$	93,188		5.36	%		Aug-15
One Commerce Square	125,089			—			3.68	%	(a)	Jan-16
Two Logan Square	88,583			89,340			7.57	%		Apr-16
Fairview Eleven Tower	21,630			22,000			4.25	%	(b)	Jan-17
Two Commerce Square	112,000			—			4.51	%	(a)	Apr-23
IRS Philadelphia Campus	190,964			197,111			7.00	%		Sep-30
Cira South Garage	40,101			42,303			7.12	%		Sep-30
Principal balance outstanding	669,762			443,942
Plus: fair market value premiums (discounts), net	389			(968		)
Total mortgage indebtedness	$	670,151		$	442,974
UNSECURED DEBT:
Credit Facility	—			69,000			LIBOR + 1.50%			Feb-16
Three-Year Term Loan - Swapped to fixed	150,000			150,000			2.60	%		Feb-15
Four-Year Term Loan	100,000			100,000			LIBOR + 1.75%			Feb-16
Seven-Year Term Loan - Swapped to fixed	200,000			200,000			3.62	%		Feb-19
$250.0M 5.400% Guaranteed Notes due 2014	218,549			238,379			5.53	%		Nov-14
$250.0M 7.500% Guaranteed Notes due 2015	157,625			166,535			7.76	%		May-15
$250.0M 6.000% Guaranteed Notes due 2016	149,919			150,429			5.95	%		Apr-16
$300.0M 5.700% Guaranteed Notes due 2017	300,000			300,000			5.68	%		May-17
$325.0M 4.950% Guaranteed Notes due 2018	325,000			325,000			5.13	%		Apr-18
$250.0M 3.950% Guaranteed Notes due 2023	250,000			250,000			4.02	%		Feb-23
Indenture IA (Preferred Trust I)	27,062			27,062			2.75	%		Mar-35
Indenture IB (Preferred Trust I)	25,774			25,774			3.30	%		Apr-35
Indenture II (Preferred Trust II)	25,774			25,774			3.09	%		Jul-35
Principal balance outstanding	1,929,703			2,027,953
plus: original issue premium (discount), net	(4,473		)	(5,597		)
Total unsecured indebtedness	$	1,925,230		$	2,022,356
Total Debt Obligations	$	2,595,381		$	2,465,330


(a)	This loan was assumed upon acquisition of the related properties on December 19, 2013. The interest rate reflects the market rate at the time of acquisition.


(b)	Represents the full debt amount of a property in a consolidated joint venture for which the Company maintains a 50% interest.

Summary of debt repurchases



Notes	Principal		Repurchase Amount		Loss on Early Extinguishment of Debt			Acceleration of Deferred Financing Amortization
2014 5.400% Notes	$	19,830	$	20,822	$	(1,020	)	$	16
2015 7.500% Notes	8,910		9,902		(1,036		)	23
2016 6.000% Notes	510		572		(63		)	1
	$	29,250	$	31,296	$	(2,119	)	$	40

Schedule of principal payments of debt obligations



2014	$	232,375
2015	409,654
2016	467,705
2017	330,323
2018	336,954
Thereafter	822,454
Total principal payments	2,599,465
Net unamortized premiums/(discounts)	(4,084		)
Outstanding indebtedness	$	2,595,381

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Schedule of financial instruments with fair values different from their carrying amount



	December 31, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Mortgage notes payable	$	669,762	$	715,244	$	443,942	$	486,412
Unsecured notes payable	$	1,401,093	$	1,471,041	$	1,430,343	$	1,553,123
Variable rate debt	$	528,610	$	526,693	$	597,610	$	595,693
Notes receivable	$	7,026	$	7,759	$	7,226	$	7,783

Risk Management and Use of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of derivative instruments in statement of financial position, fair value



Hedge Product	Hedge Type	Designation		Notional Amount				Strike		Trade Date	Maturity Date	Fair value
				12/31/2013		12/31/2012						12/31/2013			12/31/2012
Assets
Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.300	%	December 22, 2011	January 30, 2021	549			(1,262		)
Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.090	%	January 6, 2012	October 30, 2019	218			(1,129		)
				$	51,548	$	51,548					$	767		$	(2,391	)
Liabilities
Swap	Interest Rate	Cash Flow	(a)	$	200,000	$	200,000	3.623	%	December 6-13, 2011	February 1, 2019	$	(545	)	$	(8,859	)
Swap	Interest Rate	Cash Flow	(a)	77,000		77,000		2.703	%	December 9-13, 2011	February 1, 2016	(887		)	(1,343		)
Swap	Interest Rate	Cash Flow	(a)	50,000		50,000		2.470	%	December 13, 2011	February 1, 2015	(283		)	(458		)
Swap	Interest Rate	Cash Flow	(a)	23,000		23,000		2.513	%	December 7-12, 2011	May 1, 2015	(162		)	(245		)
Swap	Interest Rate	Cash Flow	(a)	27,062		27,062		2.750	%	December 21, 2011	September 30, 2017	(311		)	(914		)
				$	377,062	$	377,062					$	(2,188	)	$	(11,819	)

Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2013

Discontinued Operations and Disposal Groups [Abstract]

Revenue and expenses information for the property classified as discontinued operations



	Years ended December 31,
	2013		2012		2011
Revenue:
Rents	$	4,754	$	28,678	$	43,050
Tenant reimbursements	355		2,353		5,030
Termination fees	—		11		75
Other	123		378		110
Total revenue	5,232		31,420		48,265
Expenses:
Property operating expenses	1,839		8,687		13,940
Real estate taxes	649		3,468		5,356
Depreciation and amortization	1,921		10,208		16,178
Total operating expenses	4,409		22,363		35,474
Other income:
Interest income	2		7		3
Income from discontinued operations before gain on sale of interests in real estate	825		9,064		12,794
Net gain on disposition of discontinued operations	3,382		34,774		7,047
Income from discontinued operations	$	4,207	$	43,838	$	19,841

Beneficiaries Equity of The Parent Company (Tables)

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

Earnings per Share (EPS)

BENEFICIARIES’ EQUITY OF THE PARENT COMPANY

Earnings per Share (EPS)



	Year ended December 31,
	2013						2012						2011
	Basic			Diluted			Basic			Diluted			Basic			Diluted
Numerator
Income (loss) from continuing operations	$	38,982		$	38,982		$	(37,309	)	$	(37,309	)	$	(24,556	)	$	(24,556	)
Net (income) loss from continuing operations attributable to non-controlling interests	(357		)	(357		)	863			863			994			994
Amount allocable to unvested restricted shareholders	(363		)	(363		)	(376		)	(376		)	(505		)	(505		)
Preferred share dividends	(6,900		)	(6,900		)	(10,405		)	(10,405		)	(7,992		)	(7,992		)
Preferred share redemption charge	—			—			(4,052		)	(4,052		)	—			—
Income (loss) from continuing operations available to common shareholders	31,362			31,362			(51,279		)	(51,279		)	(32,059		)	(32,059		)
Income from discontinued operations	4,207			4,207			43,838			43,838			19,841			19,841
Discontinued operations attributable to non-controlling interests	(55		)	(55		)	(797		)	(797		)	(778		)	(778		)
Discontinued operations attributable to common shareholders	4,152			4,152			43,041			43,041			19,063			19,063
Net income (loss) attributable to common shareholders	$	35,514		$	35,514		$	(8,238	)	$	(8,238	)	$	(12,996	)	$	(12,996	)
Denominator
Weighted-average shares outstanding	153,140,458			153,140,458			143,257,097			143,257,097			135,444,424			135,444,424
Contingent securities/Share based compensation	—			1,273,853			—			—			—			—
Total weighted-average shares outstanding	153,140,458			154,414,311			143,257,097			143,257,097			135,444,424			135,444,424
Earnings per Common Share:
Income (loss) from continuing operations attributable to common shareholders	$	0.20		$	0.20		$	(0.36	)	$	(0.36	)	$	(0.24	)	$	(0.24	)
Discontinued operations attributable to common shareholders	0.03			0.03			0.30			0.30			0.14			0.14
Net income (loss) attributable to common shareholders	$	0.23		$	0.23		$	(0.06	)	$	(0.06	)	$	(0.10	)	$	(0.10	)

Partners Equity of The Operating Partnership (Tables)

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

Earnings per Common Partnership Unit

PARTNERS’ EQUITY OF THE OPERATING PARTNERSHIP

Earnings per Common Partnership Unit



	Year ended December 31,
	2013						2012						2011
	Basic			Diluted			Basic			Diluted			Basic			Diluted
Numerator
Income (loss) from continuing operations	$	38,982		$	38,982		$	(37,309	)	$	(37,309	)	$	(24,556	)	$	(24,556	)
Amount allocable to unvested restricted unitholders	(363		)	(363		)	(376		)	(376		)	(505		)	(505		)
Preferred unit dividends	(6,900		)	(6,900		)	(10,405		)	(10,405		)	(7,992		)	(7,992		)
Preferred unit redemption charge	—			—			(4,052		)	(4,052		)	—			—
Income (loss) from continuing operations available to common unitholders	31,719			31,719			(52,142		)	(52,142		)	(33,053		)	(33,053		)
Discontinued operations attributable to common unitholders	4,207			4,207			43,838			43,838			19,841			19,841
Net income (loss) attributable to common unitholders	$	35,926		$	35,926		$	(8,304	)	$	(8,304	)	$	(13,212	)	$	(13,212	)
Denominator
Weighted-average units outstanding	154,929,545			154,929,545			145,883,217			145,883,217			145,118,841			145,118,841
Contingent securities/Share based compensation	—			1,273,853			—			—			—			—
Total weighted-average units outstanding	154,929,545			156,203,398			145,883,217			145,883,217			145,118,841			145,118,841
Earnings per Common Partnership Unit:
Income (loss) from continuing operations attributable to common unitholders	$	0.20		$	0.20		$	(0.36	)	$	(0.36	)	$	(0.23	)	$	(0.23	)
Discontinued operations attributable to common unitholders	0.03			0.03			0.30			0.30			0.14			0.14
Net income (loss) attributable to common unitholders	$	0.23		$	0.23		$	(0.06	)	$	(0.06	)	$	(0.09	)	$	(0.09	)

Share Based and Deferred Compensation (Tables)

12 Months Ended

Dec. 31, 2013

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Option activity



	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at January 1, 2013	3,337,549		$	14.85	5.95	$	—
Exercised	(236,318	)	$	9.86
Forfeited/Expired	(117,662	)	$	18.61
Outstanding at December 31, 2013	2,983,569		$	15.50	5.15	$	—
Vested/Exercisable at December 31, 2013	2,799,140		$	15.74	5.05	$	—

Company's restricted share activity



	Shares		Weighted Average Grant Date Fair value
Non-vested at January 1, 2013	597,708		$	12.57
Granted	182,576		13.13
Vested	(208,306	)	13.13
Forfeited	(8,265	)	11.41
Non-vested at December 31, 2013	563,713		$	12.56

Distributions Distributions (Tables)

12 Months Ended

Dec. 31, 2013

Distributions [Abstract]

Schedule of Dividends Payable [Table Text Block]

DISTRIBUTIONS



	Years ended December 31,
	2013			2012			2011
	(in thousands, except per share amounts)
Common Share Distributions:
Ordinary income	$	0.52		$	0.39		$	0.37
Capital gain	—			—			—
Non-taxable distributions	0.08			0.21			0.23
Distributions per share	$	0.60		$	0.60		$	0.60
Percentage classified as ordinary income	87.00		%	65.00		%	61.67		%
Percentage classified as capital gain	—		%	—		%	—		%
Percentage classified as non-taxable distribution	13.00		%	35.00		%	38.33		%
Preferred Share Distributions:
Total distributions declared	$	6,900		$	10,405		$	7,992
Percentage classified as ordinary income	100.00		%	100.00		%	100.00		%

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2013

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]



Parent Company	Cash Flow Hedges
Balance at January 1, 2011	$	(1,945	)
Change during year	(4,499		)
Non-controlling interest — consolidated real estate venture partner’s share of unrealized (gains)/losses on derivative financial instruments	212
Reclassification adjustments for (gains) losses reclassified into operations	153
Balance at December 31, 2011	$	(6,079	)
Change during year	(7,338		)
Non-controlling interest — consolidated real estate venture partner’s share of unrealized (gains)/losses on derivative financial instruments	187
Settlement of interest rate swaps	(2,985		)
Reclassification adjustments for (gains) losses reclassified into operations	297
Balance at December 31, 2012	$	(15,918	)
Change during year	12,789
Non-controlling interest — consolidated real estate venture partner’s share of unrealized (gains)/losses on derivative financial instruments	(152		)
Reclassification adjustments for (gains) losses reclassified into operations	286
Balance at December 31, 2013	$	(2,995	)



Operating Partnership	Cash Flow Hedges
Balance at January 1, 2011	$	(2,080	)
Change during year	(4,499		)
Reclassification adjustments for (gains) losses reclassified into operations	153
Balance at December 31, 2011	$	(6,426	)
Change during year	(7,338		)
Settlement of interest rate swaps	(2,985		)
Reclassification adjustments for (gains) losses reclassified into operations	297
Balance at December 31, 2012	$	(16,452	)
Change during year	12,789
Reclassification adjustments for (gains) losses reclassified into operations	286
Balance at December 31, 2013	$	(3,377	)

Segment Information (Tables)

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

Segment information



	Pennsylvania Suburbs		Philadelphia CBD		Metropolitan Washington, D.C.			New Jersey/Delaware		Richmond, Virginia		Austin, Texas (a)			California		Corporate			Total
2013
Real estate investments, at cost:
Operating properties	$	1,199,105	$	1,300,666	$	1,214,965		$	414,716	$	310,397	$	36,856		$	192,584	$	—		$	4,669,289
Construction-in-progress																	74,174			74,174
Land inventory																	93,351			93,351
Total revenue	$	153,426	$	146,081	$	116,048		$	60,262	$	35,058	$	31,451		$	18,369	$	1,515		$	562,210
Property operating expenses, real estate taxes and third party management expenses	54,506		55,702		42,641			29,981		14,916		13,298			9,411		1,314			221,769
Net operating income	$	98,920	$	90,379	$	73,407		$	30,281	$	20,142	$	18,153		$	8,958	$	201		$	340,441

Investment in real estate ventures, at equity	$	17,272	$	19,975	$	59,905		$	—	$	1,400	$	81,960		$	—	$	—		$	180,512
Equity in income of real estate ventures	$	925	$	1,547	$	130		$	1,245	$	381	$	(564	)	$	—	$	—		$	3,664

2012
Real estate investments, at cost:
Operating properties	$	1,178,730	$	988,590	$	1,193,200		$	546,644	$	309,923	$	285,346		$	223,736	$	—		$	4,726,169
Construction-in-progress																	48,950			48,950
Land inventory																	102,439			102,439
Total revenue	$	150,075	$	131,592	$	107,656		$	59,671	$	35,701	$	32,379		$	17,463	$	1,142		$	535,679
Property operating expenses, real estate taxes and third party management expenses	52,657		50,787		41,485			28,506		14,484		13,951			9,043		(65		)	210,848
Net operating income	$	97,418	$	80,805	$	66,171		$	31,165	$	21,217	$	18,428		$	8,420	$	1,207		$	324,831

Investment in real estate ventures, at equity	$	33,160	$	27,859	$	49,169		$	17,294	$	1,245	$	64,828		$	—	$	—		$	193,555
Equity in income of real estate ventures	$	520	$	1,113	$	(648	)	$	1,803	$	269	$	(316	)	$	—	$	—		$	2,741

2011
Operating properties	$	1,218,071	$	953,870	$	1,255,803		$	545,657	$	307,698	$	257,694		$	254,287	$	—		$	4,793,080
Construction-in-progress																	25,083			25,083
Land inventory																	109,008			109,008
Total revenue	$	148,887	$	125,366	$	119,255		$	58,960	$	36,789	$	30,894		$	16,692	$	1,725		$	538,568
Property operating expenses, real estate taxes and third party management expenses	54,734		48,831		45,135			30,564		14,739		13,034			9,407		347			216,791
Net operating income	$	94,153	$	76,535	$	74,120		$	28,396	$	22,050	$	17,860		$	7,285	$	1,378		$	321,777

Investment in real estate ventures, at equity	$	5,264	$	13,397	$	24,671		$	6,168	$	1,163	$	65,144		$	—	$	—		$	115,807
Equity in income of real estate ventures	$	1,861	$	466	$	(277	)	$	1,157	$	510	$	58		$	—	$	—		$	3,775

Reconciliation of consolidated net operating income



	Years Ended December 31,
	2013			2012			2011

Consolidated net operating income	$	340,441		$	324,831		$	321,777
Less:
Interest expense	(121,937		)	(132,939		)	(131,405		)
Interest expense - amortization of deferred financing costs	(4,676		)	(6,208		)	(4,991		)
Interest expense - financing obligation	(972		)	(850		)	—
Depreciation and amortization	(197,021		)	(188,382		)	(202,933		)
General and administrative expenses	(27,628		)	(25,413		)	(24,602		)
Plus:
Interest income	1,044			3,008			1,810
Historic tax credit transaction income	11,853			11,840			12,026
Recognized hedge activity	—			(2,985		)	—
Equity in income of real estate ventures	3,664			2,741			3,775
Net gain from remeasurement of investments in real estate ventures	6,866			—			—
Net gain on sales of interests in real estate	—			—			2,985
Net loss on sale of undepreciated real estate	(137		)	—			—
Net gain (loss) on real estate venture transactions	29,604			(950		)	(222		)
Loss on early extinguishment of debt	(2,119		)	(22,002		)	(2,776		)
Income (loss) from continuing operations	38,982			(37,309		)	(24,556		)
Income from discontinued operations	4,207			43,838			19,841
Net income (loss)	$	43,189		$	6,529		$	(4,715	)

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2013

Operating Leases [Abstract]

Operating Leases Future Minimum Payments Due [Table Text Block]



Year	Minimum Rent
2014	$	471,918
2015	457,315
2016	416,467
2017	358,368
2018	299,619
Thereafter	1,403,003

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2013

Commitments and Contingencies Disclosure [Abstract]

Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block]



Year	Minimum Rent
2014	$	1,303
2015	1,303
2016	1,303
2017	1,303
2018	1,303
Thereafter	57,540
Total	64,055

Summary of Quarterly Results (Tables)

12 Months Ended

Dec. 31, 2013

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]



	1st Quarter		2nd Quarter		3rd Quarter		4th Quarter (a)
2013
Total revenue	$	139,554	$	140,644	$	143,354	$	138,658
Net income (loss)	3,919		7,180		11,088		21,002
Net income (loss) allocated to Common Shares	2,058		5,308		9,173		18,975
Basic earnings (loss) per Common Share	$	0.01	$	0.03	$	0.06	$	0.12
Diluted earnings (loss) per Common Share	$	0.01	$	0.03	$	0.06	$	0.12
2012
Total revenue	$	133,516	$	131,530	$	134,238	$	136,395
Net income (loss)	9,336		6,802		17,089		(26,698		)
Net income (loss) allocated to Common Shares	7,108		1,537		13,949		(30,832		)
Basic earnings (loss) per Common Share	$	0.05	$	0.01	$	0.10	$	(0.21	)
Diluted earnings (loss) per Common Share	$	0.05	$	0.01	$	0.10	$	(0.21	)

Organization of The Parent Company and The Operating Partnership (Details) ft² in Millions	Dec. 31, 2013 a ft² Properties Real_Estate_Investments Rate
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Area of undeveloped parcels of land (in acres) owned by a Real Estate Venture \| a	3.8
Parent Company [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Ownership in the Operating Partnership	98.80%
Net rentable square feet \| ft²	24.8
Area Owned by Company of Undeveloped Parcels Of Land \| a	432
Area of additional undeveloped parcels of land with option to purchase \| a	51
Total potential development capacity \| ft²	6.8
Unconsolidated real estate ventures [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of unconsolidated real estate ventures \| Real_Estate_Investments	17
Net rentable square feet \| ft²	5.7
Wholly-owned management company subsidiaries [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Net rentable square feet \| ft²	32.7
Third Parties and Unconsolidated Real Estate Ventures [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Net rentable square feet \| ft²	7.9
Subsidiaries [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Ownership in the Operating Partnership \| Rate	100.00%
Total Properties [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	204
Office Properties [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	176
Industrial facilities [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	19
Mixed-use properties [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	5
Development Property [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	1
Redevelopment Property [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	2
Re-entitlement Property [Member]
Organization of The Parent Company and The Operating Partnership (Textuals) [Abstract]
Number of properties with ownership interest	1

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 02, 2010
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Revenue increased by straight-line rent adjustment				$ 17.7	$ 21.1	$ 17.9
Increased revenue due to amortization of deferred rent				2.4		2.4
Decrease in revenue due to amortization of lease incentives				$ 0.7	0.8	1.6
Increase in shares due to amendments in plan, shares solely available for options and share appreciation rights				2,983,569			3,600,000
Increase in Common shares available for future awards							6,000,000
Common shares available for future awards				5,195,177
Options awarded, term				one to ten-year
Award vesting term, minimum				1 year
Award vesting term, maximum				10 years
Stock-based compensation expense				$ 8.3	8.6	6.4
Stock-based compensation expense, capitalized				1.4	$ 2.6	1.5
Treasury Stock, Shares	0				0
Restatement Adjustment [Member]
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Out of period stock compensation expense adjustment	$ 0.6
Overstatement (Understatement) of Expense due to Out of Period Adjustment	$ 0.6	$ (0.2)	$ (0.3)			$ (0.1)
The Grove at Cira Centre South [Member]
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Guarantor Obligations, Current Carrying Value				24.7
PJP VII [Member]
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Guarantor Obligations, Current Carrying Value				0.5
Subsidiaries [Member]
Summary of Significant Accounting Policies [Line Items]
Tax Basis of Assets, Cost for Income Tax Purposes				4,000.0
TB-BDN Plymouth Apartments [Member]
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Guarantor Obligations, Current Carrying Value				$ 3.2

Summary of Significant Accounting Policies (Fair Value Measurements) (Details) - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 767
Available-for-sale Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Available-for-sale Securities [Member] \| Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Interest Rate Swap [Member]
Liabilities:
Interest Rate Swaps	2,188	$ 14,210
Interest Rate Swap [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Liabilities:
Interest Rate Swaps	0	0
Interest Rate Swap [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	767
Liabilities:
Interest Rate Swaps	2,188	14,210
Interest Rate Swap [Member] \| Unobservable Inputs (Level 3) [Member]
Liabilities:
Interest Rate Swaps	$ 0	$ 0

Summary of Significant Accounting Policies (Notes Receivable) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($) Properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable	$ 13,000	$ 13,500
Tenant receivables and accrued rent receivables, gross	3,200	3,100
Notes receivable	7,026	7,226
Investment Income, Interest	$ 1,044	3,008	$ 1,810
Purchase money mortgage loan repayments terms	12/31/2012
20 Year Amortization Period [Member] \| Purchase money mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable	$ 7,000	7,200
Interest rate	8.50%
Notes receivable amortization period, years	20 years		20 years
Due 2016 [Member] \| Purchase money mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable amortization period, years	7 years		7 years
Proceeds from Collection of Notes Receivable	$ 23,500
Trenton Properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of properties sold \| Properties			2
Gross deferred gain on sale of properties		$ 12,900
Investment Income, Interest	$ 1,000

Summary of Significant Accounting Policies Construction in Progress (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Construction in Progress [Line Items]
Internal direct construction costs capitalized related to development of properties and land holdings	$ 3,700	$ 4,700	$ 4,000
Interest Costs Capitalized	2,600	2,600	2,000
Salaries including bonuses and benefits, capitalized during the period	3,673	4,669	4,034
Development [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	156	57	0
Redevelopment [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	194	353	0
Tenant Improvements [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	$ 3,323	$ 4,259	$ 4,034

Summary of Significant Accounting Policies Schedule of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Other Assets [Abstract]
Other Assets	$ 62,377	$ 53,325

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Principles of Consolidation/Depreciation and Amortization) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Dec. 31, 2006
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Depreciation and amortization expense relating to intangibles	$ 4.7	$ 1.7	$ 1.4	$ 1.8	$ 1.7	$ 1.5

Summary of Significant Accounting Policies Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2011
Income Tax Contingency [Line Items]
Increase In Revenue Due To Amortization Of Deferred Rent	$ 2.4	$ 2.4
Distributable Income Minimum Percentage	90.00%
Federal excise tax if sufficient taxable income is not distributed within prescribed time limits	4.00%
Excise tax equal to annual amount	4.00%
Excise tax, if sum of ordinary income	85.00%
Excise tax, if Net capital gain exceeds cash distributions and certain taxes paid	95.00%
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Income Tax Contingency [Line Items]
Tax Basis of Assets, Cost for Income Tax Purposes	$ 4,000.0

Real Estate Investments Real Estate Investments, Business Combinations (Details) $ in Thousands	Dec. 19, 2013 USD ($)
One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$ 255,705
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	85,036
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	(8,637)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	332,104
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(238,082)
Business Combination, return of capital on equity method investment	(30,424)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	10,423
Business Combination, Total Cash Payment at Settlement	73,075
In-place lease value [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 80,916
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 10 months 24 days
Above Market Leases [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 4,120
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 10 months 24 days
Finite-Lived Intangible Assets [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 85,036
Below market leases acquired [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ (8,637)
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 6 months
Subsidiaries [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	$ (946)

Real Estate Investments Real Estate Investments, Pro Forma of Acquired Properties (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pro Forma [Abstract]
Business Acquisition, Pro Forma Revenue									$ 610,979	$ 592,753
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax									21,805	(60,011)
Business Acquisition, Pro Forma Net Income (Loss)									$ 25,957	$ (16,970)
Continuing operations (in dollars per share)									$ 0.20	$ (0.36)	$ (0.24)
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic									0.14	(0.42)
Income (Loss) from Continuing Operations, Per Diluted Share									0.20	(0.36)	(0.24)
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted									0.14	(0.42)
Earnings Per Share, Basic	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	0.23	(0.06)	(0.10)
Pro Forma, Earnings Per Share, Basic									0.17	(0.12)
Earnings Per Share, Diluted	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	0.23	(0.06)	$ (0.10)
Pro Forma Earnings Per Share, Diluted									$ 0.17	$ (0.12)

Real Estate Investments, Gross Carrying Value of Company's Properties (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Gross carrying value of rental properties
Land	$ 680,513	$ 662,107
Building and improvements	3,504,060	3,576,065
Tenant improvements	484,716	487,997
Rental properties	$ 4,669,289	$ 4,726,169	$ 4,793,080

Real Estate Investments Real Estate Investments, Acquisitions and Dispositions (Details) $ / shares in Units, $ in Thousands																3 Months Ended								12 Months Ended
	Dec. 19, 2013 USD ($) a ft² Storey Rate	Oct. 17, 2013 USD ($) ft²	Jun. 28, 2013 USD ($) ft²	Jun. 19, 2013 USD ($) ft²	Jun. 14, 2013 USD ($) ft²	Apr. 25, 2013 USD ($) a	Dec. 31, 2012 USD ($) ft²	Dec. 11, 2012 USD ($) ft²	Nov. 20, 2012 USD ($) ft²	Jul. 18, 2012 USD ($) ft²	Jul. 10, 2012 USD ($) ft² Properties	Jun. 22, 2012 USD ($) ft²	Mar. 22, 2012 USD ($) ft²	Jan. 17, 2012 USD ($) ft²	Jan. 06, 2012 USD ($) ft²	Dec. 31, 2013 USD ($) a ft² $ / shares	Sep. 30, 2013 $ / shares	Jun. 30, 2013 $ / shares	Mar. 31, 2013 $ / shares	Dec. 31, 2012 USD ($) ft² $ / shares	Sep. 30, 2012 $ / shares	Jun. 30, 2012 $ / shares	Mar. 31, 2012 $ / shares	Feb. 25, 2014 USD ($)	Dec. 31, 2013 USD ($) a ft² $ / shares	Dec. 31, 2012 USD ($) ft² $ / shares	Dec. 31, 2011 USD ($) $ / shares	Nov. 19, 2013 USD ($) a	Aug. 05, 2013 USD ($) a	Feb. 25, 2013 USD ($) ft² Properties	Sep. 05, 2012 USD ($) a
Significant Acquisitions and Disposals [Line Items]
Business Acquisition, Pro Forma Revenue																									$ 610,979	$ 592,753
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual																									3,400
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual																									200
Net gain from remeasurement of investments in real estate ventures																									6,866	0	$ 0
Adjustment to Record Land Acquisition to Fair Value																									7,752	0	0
Payments to Acquire Real Estate																									161,604	77,555	40,674
Gains (Losses) on Sales of Investment Real Estate																									0	0	2,985
Equity Method Investments							$ 193,555									$ 180,512				$ 193,555					180,512	193,555	115,807
Secured Debt							442,974									670,151				442,974					670,151	442,974
Balance of the Financing Obligation							55,826									$ 32,923				$ 55,826					32,923	55,826
Gain (Loss) on Sale of Properties																									3,382	34,774	7,047
Net gain (loss) on sale of undepreciated real estate																									$ (137)	0	$ 0
Area Owned By Real Estate Venture Of Undeveloped Parcels Of Land \| a																3.8									3.8
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax																									$ 21,805	(60,011)
Business Acquisition, Pro Forma Net Income (Loss)																									$ 25,957	$ (16,970)
Continuing operations (in dollars per share) \| $ / shares																									$ 0.20	$ (0.36)	$ (0.24)
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic \| $ / shares																									0.14	(0.42)
Income (Loss) from Continuing Operations, Per Diluted Share \| $ / shares																									0.20	(0.36)	(0.24)
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted \| $ / shares																									0.14	(0.42)
Earnings Per Share, Basic \| $ / shares																$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05		0.23	(0.06)	(0.10)
Pro Forma, Earnings Per Share, Basic \| $ / shares																									0.17	(0.12)
Earnings Per Share, Diluted \| $ / shares																$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05		0.23	(0.06)	$ (0.10)
Pro Forma Earnings Per Share, Diluted \| $ / shares																									$ 0.17	$ (0.12)
Other Assets							53,325									$ 62,377				$ 53,325					$ 62,377	$ 53,325
One and Two Commerce Square [Member]
Significant Acquisitions and Disposals [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage	99.00%
Net gain from remeasurement of investments in real estate ventures	$ 981
Number of floors of a building \| Storey	41
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds	$ 331,800
Business Combination, Assumption of Existing Mortgage Debt	237,100
Lease percentage of acquired property																86.70%									86.70%
Net rentable space of property acquired \| ft²																1,896,142									1,896,142
Acquisition related costs	$ 900
Settlement period to finalize a business combination	60 days
Other Assets	$ 2,100
Four Points Centre [Member]
Significant Acquisitions and Disposals [Line Items]
Number of floors of a building \| Storey	3
Area of Land \| a	22.3
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds	$ 47,300
Lease percentage of acquired property	99.20%
Business Acquisition Purchase Price Allocation Intangible Assets	$ 6,500
Business Acquisition Purchase Price Allocated To Market Lease Liabilities	$ 1,000
Net rentable space of property acquired \| ft²	192,396
Acquisition related costs	$ 100
Business Acquisition Purchase Price Allocation Building	36,000
Business Acquisition Purchase Price Allocation, Land Portion	5,800
Cira Ground Land Parcel [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land \| a																												0.8
Ground Lease Buy-out, Total Cost																												$ 24,600
Accrued Rent																												12,100
Acquisition related costs																												$ 1,400
TB-BDN Plymouth Apartments [Member]
Significant Acquisitions and Disposals [Line Items]
Company's Ownership Percentage in the Real Estate Venture																															50.00%
Other Ownership Interests, Contributed Capital																															$ 15,500
Number of Units in Real Estate Property																															398
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures							15,200													15,200						15,200
Permanent Basis Adjustment Between Carrying Value And Fair Value							300													300						300
Area Owned By Real Estate Venture Of Undeveloped Parcels Of Land \| a																															20
7400 West at Lantana [Member]
Significant Acquisitions and Disposals [Line Items]
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds							32,100
Business Acquisition Purchase Price Allocation Intangible Assets							8,400													8,400						8,400
Business Acquisition Purchase Price Allocated To Market Lease Liabilities							$ 1,900													$ 1,900						$ 1,900
Net rentable space of property acquired \| ft²							136,075													136,075						136,075
Acquisition related costs							$ 100													$ 100						$ 100
Business Acquisition Purchase Price Allocation Building							20,900													20,900						20,900
Business Acquisition Purchase Price Allocation, Land Portion							4,700													4,700						4,700
Wood Oak Drive Land [Member]
Significant Acquisitions and Disposals [Line Items]
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds									$ 2,100
Net rentable space of property acquired \| ft²									10
1900 Market [Member]
Significant Acquisitions and Disposals [Line Items]
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds								$ 34,800
Business Acquisition Purchase Price Allocation Intangible Assets								13,500
Business Acquisition Purchase Price Allocated To Market Lease Liabilities								$ 3,800
Net rentable space of property acquired \| ft²								456,922
Acquisition related costs								$ 100
Business Acquisition Purchase Price Allocation Building								17,300
Business Acquisition Purchase Price Allocation, Land Portion								$ 7,800
Plymouth Meeting, Pennsylvania [Member]
Significant Acquisitions and Disposals [Line Items]
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds															$ 9,100
Net rentable space of property acquired \| ft²															154,392
Acquisition related costs															$ 100
875 First Avenue [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties	$ 100
Net rentable square feet of properties sold \| ft²	50,000
Sales price of properties sold	$ 3,800
1336 Enterprise Drive [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties		$ 200
Net rentable square feet of properties sold \| ft²		39,330
Sales price of properties sold		$ 2,600
Dabney Land, East [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land \| a																													8
Sales price of properties sold																													$ 500
Net gain (loss) on sale of undepreciated real estate																									$ (100)
Pacific View Plaza [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties					$ (500)
Net rentable square feet of properties sold \| ft²					51,695
Sales price of properties sold					$ 10,300
Princeton Pike Corporate Center [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties																								$ 5,300
Number of flex/office properties sold \| Properties																														8
Net rentable square feet of properties sold \| ft²																														800,546
Sales price of properties sold																														$ 121,000
Oaklands Corporate Center [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties										$ 9,900
Number of flex/office properties sold										11
Net rentable square feet of properties sold \| ft²										466,719
Sales price of properties sold										$ 52,700
Pacific Ridge Corporate Center [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties												$ (2,800)
Net rentable square feet of properties sold \| ft²												121,381
Sales price of properties sold												$ 29,000
South Lake at Dulles Corner [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties													$ 14,500
Net rentable square feet of properties sold \| ft²													268,240
Sales price of properties sold													$ 91,100
304 Harper Drive [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties														$ 200
Net rentable square feet of properties sold \| ft²														32,978
Sales price of properties sold														$ 3,000
The Bluffs [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties			$ (900)
Net rentable square feet of properties sold \| ft²			68,708
Sales price of properties sold			$ 18,000
100 Arrandale Boulevard [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties			$ (400)
Net rentable square feet of properties sold \| ft²			34,931
Sales price of properties sold			$ 3,500
1700 Paoli Pike [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Sale of Properties				$ (400)
Net rentable square feet of properties sold \| ft²				28,000
Sales price of properties sold				$ 2,700
Brandywine - Al Venture [Member]
Significant Acquisitions and Disposals [Line Items]
Proceeds from Real Estate and Real Estate Joint Ventures											$ 120,600
Equity Method Investments																$ 46,406									$ 46,406
Company's Ownership Percentage in the Real Estate Venture																50.00%									50.00%
Net rentable space of property acquired \| ft²											497,896
Amount Contributed Net of Closing Costs and Customary Prorations											$ 26,100
Number of Real Estate Properties \| Properties											3
Three Logan Square [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land \| a						1.8
Ground Lease Buy-out, Total Cost						$ 20,800
Adjustment to Record Land Acquisition to Fair Value						4,300
Acquisition related costs						$ 100
Secured Debt [Member]
Significant Acquisitions and Disposals [Line Items]
Long-term Debt, Gross							443,942									$ 669,762				443,942					$ 669,762	443,942
Secured Debt							442,974									670,151				442,974					670,151	442,974
Secured Debt [Member] \| Two Commerce Square [Member]
Significant Acquisitions and Disposals [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate \| Rate	3.96%
Long-term Debt, Fair Value	$ 107,900
Long-term Debt, Gross	$ 112,000
Secured Debt [Member] \| One Commerce Square [Member]
Significant Acquisitions and Disposals [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate \| Rate	5.67%
Long-term Debt, Fair Value	$ 130,200
Long-term Debt, Gross	$ 125,100
Subsidiaries [Member]
Significant Acquisitions and Disposals [Line Items]
Net gain from remeasurement of investments in real estate ventures																									6,866	0	$ 0
Adjustment to Record Land Acquisition to Fair Value																									7,752	0
Payments to Acquire Real Estate																									161,604	77,555	40,674
Gains (Losses) on Sales of Investment Real Estate																									0	0	2,985
Equity Method Investments							193,555									180,512				193,555					180,512	193,555
Secured Debt							442,974									670,151				442,974					670,151	442,974
Balance of the Financing Obligation							55,826									32,923				55,826					32,923	55,826
Gain (Loss) on Sale of Properties																									3,382	34,774	7,047
Net gain (loss) on sale of undepreciated real estate																									$ (137)	$ 0	$ 0
Continuing operations (in dollars per share) \| $ / shares																									$ 0.20	$ (0.36)	$ (0.23)
Income (Loss) from Continuing Operations, Per Diluted Share \| $ / shares																									0.20	(0.36)	(0.23)
Earnings Per Share, Basic \| $ / shares																									0.23	(0.06)	(0.09)
Earnings Per Share, Diluted \| $ / shares																									$ 0.23	$ (0.06)	$ (0.09)
Other Assets							$ 53,325									$ 62,377				$ 53,325					$ 62,377	$ 53,325

Investment in Unconsolidated Ventures (Narrative) (Details)
$ in Thousands

12 Months Ended

Oct. 16, 2013

USD ($)

ft²

Properties

Jul. 31, 2013

USD ($)

Jun. 19, 2013

USD ($)

Dec. 31, 2013

USD ($)

ft²

Buildings

Real_Estate_Ventures

Room

Dec. 31, 2012

USD ($)

Dec. 31, 2011

USD ($)

Mar. 26, 2013

USD ($)

Rate

Jan. 25, 2013

USD ($)

Storey

beds

Schedule of Equity Method Investments [Line Items]

Net gain (loss) on real estate venture transactions

$ 29,604

$ (950)

$ (222)

Proceeds from Equity Method Investment, Dividends or Distributions

7,496

5,109

10,316

Payments to Acquire Equity Method Investments

33,069

65,354

5,277

Company's share of equity (Company's basis)

180,512

193,555

115,807

Net gain on real estate venture transactions

$ 3,683

Number of unconsolidated Real Estate Ventures | Real_Estate_Ventures

Number of real estate ventures that owns 51 office buildings | Real_Estate_Ventures

Number of office buildings owned by 15 Real Estate Ventures | Buildings

Net rentable square feet of 51 office buildings owned the 15 Real Estate Ventures | ft²

5,700,000

Number of real estate ventures that owns undeveloped land | Real_Estate_Ventures

Area of undeveloped parcels of land (in acres) owned by a Real Estate Venture | a

3.8

Number of real estate ventures that owns land under development | Real_Estate_Ventures

Area Owned By Real Estate Venture in Parcels Of Land Under Development | a

22.5

Number of real estate ventures developed hotel property | Real_Estate_Ventures

Number of rooms in a hotel property developed by one Real Estate Venture | Room

137

Minimum ownership interest in unconsolidated Real Estate Ventures

20.00%

Maximum ownership interest in unconsolidated Real Estate Ventures

65.00%

Net gain from remeasurement of investments in real estate ventures

$ 6,866

$ 0

BDN Beacon Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

20.00%

Company's share of equity (Company's basis)

$ 0

$ 17,000

Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Company's share of equity (Company's basis)

$ 17,262

Two Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[1]

35.00%

Company's share of equity (Company's basis)

$ (100)

$ 0

Net gain on real estate venture transactions

$ 3,683

Investments, Fair Value Disclosure

3,600

4040 Wilson Venture [Member]

Schedule of Equity Method Investments [Line Items]

Area of Real Estate Property | ft²

426,900

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investment, Budgeted Total Project Cost

$ 194,100

Payments to Acquire Equity Method Investments

72,000

Construction Loan

$ 125,100

Company's share of equity (Company's basis)

$ 13,499

Area of undeveloped parcels of land (in acres) owned by a Real Estate Venture | a

1.3

Six Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[2]

63.00%

Company's share of equity (Company's basis)

$ 0

Net gain from remeasurement of investments in real estate ventures

7,800

Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value

24,500

Business Acquisition Purchase Price Allocation Building

14,800

Business Acquisition Purchase Price Allocation, Land Portion

6,900

Business Acquisition Purchase Price Allocation Intangible Assets

3,300

Business Acquisition Purchase Price Allocated To Market Lease Liabilities

$ 500

The Grove at Cira Centre South [Member]

Schedule of Equity Method Investments [Line Items]

Number of floors of a building | Storey

Student housing bed capacity | beds

850

Equity Method Investment, Budgeted Total Project Cost

158,500

Payments to Acquire Equity Method Investments

60,700

Construction Loan

97,800

Equity Method Investment, Aggregate Cost

$ 4,000

Area of undeveloped parcels of land (in acres) owned by a Real Estate Venture | a

Equity Method Investment, Underlying Equity in Net Assets

$ 8,500

Equity Method Investment, Difference Between Carrying Amount and Underlying Equity

$ 4,500

TB-BDN Plymouth Apartments [Member]

Schedule of Equity Method Investments [Line Items]

Guarantor Obligations, Current Carrying Value

3,200

PJP VII [Member]

Schedule of Equity Method Investments [Line Items]

Guarantor Obligations, Current Carrying Value

500

The Grove at Cira Centre South [Member]

Schedule of Equity Method Investments [Line Items]

Guarantor Obligations, Current Carrying Value

24,700

Ashton Park [Member] | 4040 Wilson Venture [Member]

Schedule of Equity Method Investments [Line Items]

Fair value of land, net of amount encumbered

$ 36,000

Brandywine Realty Trust [Member] | Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Number of properties contributed to a joint venture | Properties

Area of Real Estate Property | ft²

1,398,826

Aggregate gross sales price of a joint venture

$ 330,000

Equity method investment, agreement to pay future capital expenditures

5,200

Potential future capital contributions under joint ventures which are not contractually binding

$ 100,000

Net gain (loss) on real estate venture transactions

25,900

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investment, Additional Distribution Rights

10.00%

Brandywine Realty Trust [Member] | 4040 Wilson Venture [Member]

Schedule of Equity Method Investments [Line Items]

Equity method investment, agreement to pay future capital expenditures

$ 800

Payments to Acquire Interest in Joint Venture

$ 36,000

$ 13,500

DRA Advisors LLC [Member] | Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Distribution, Net of Initial Funding Agreement

266,300

Amount Of Participant Contribution

49,700

Equity method investments, Closing costs

1,900

Closing Prorations and Lender Holdbacks

6,900

Proceeds from Equity Method Investment, Dividends or Distributions

$ 271,500

Equity Method Investment, Ownership Percentage

50.00%

Non-Recourse Debt

$ 230,600

Campus Crest Properties, LLC [Member] | The Grove at Cira Centre South [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

30.00%

HSRE, LLC [Member] [Member] | The Grove at Cira Centre South [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

40.00%

[1]	(i)The ownership interest in these properties was disposed of prior to December 31, 2013. For further information on BDN Beacon LLC, see the section entitled BDN Beacon Venture below. For further information on Two Tower Bridge, see the section entitled Two and Six Tower Bridge Exchange Transaction below.
[2]	(g)On June 19, 2013, we acquired ownership of Six Tower Bridge. Real estate venture income reflects our previous partnership interest for the year to date period through June 18, 2013.

Investment in Unconsolidated Ventures (Financial Position of Unconsolidated Real Estate Ventures) (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financial position of the Real Estate Ventures
Equity Method Investment Summarized Financial Information Debt	$ 699,860
Company's share of equity (Company's basis)	180,512	$ 193,555	$ 115,807
Unconsolidated real estate ventures [Member]
Financial position of the Real Estate Ventures
Net property	965,475	923,536
Other Assets	164,152	174,677
Other Liabilities	49,442	53,645
Equity Method Investment Summarized Financial Information Debt	699,860	724,780
Equity	380,325	319,788
Company's share of equity (Company's basis)	$ 180,512	$ 193,555

Investment in Unconsolidated Ventures (Summary of Results of Operations of Unconsolidated Real Estate Ventures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of results of operations of Real Estate Ventures
Income (Loss) from Equity Method Investments	$ 3,664	$ 2,741	$ 3,775
Unconsolidated real estate ventures [Member]
Summary of results of operations of Real Estate Ventures
Revenue	102,919	164,013	145,867
Operating expenses	40,436	70,775	63,715
Interest expense, net	26,529	41,633	42,032
Depreciation and amortization	35,138	50,241	39,172
Net income	816	1,364	948
Income (Loss) from Equity Method Investments	$ 3,664	$ 2,741	$ 3,775

Investment in Unconsolidated Ventures Company's Investment in Real Estate Ventures and the Company's Share of the Real Estate Ventures' Income (Loss) (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2013

USD ($)

Fixed_Rate_Mortgages

Rate

Dec. 31, 2012

USD ($)

Dec. 31, 2011

USD ($)

Jul. 31, 2013

Jun. 19, 2013

USD ($)

Mar. 26, 2013

USD ($)

Rate

Schedule of Equity Method Investments [Line Items]

Area Owned By Real Estate Venture Of Undeveloped Parcels Of Land | a

3.8

Equity Method Investments

$ 180,512

$ 193,555

$ 115,807

Income (Loss) from Equity Method Investments

3,664

2,741

3,775

Equity Method Investment Summarized Financial Information Debt

699,860

Proceeds from Equity Method Investment, Dividends or Distributions

$ 7,496

$ 5,109

$ 10,316

Broadmoor Austin Associates [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[1]

50.00%

Equity Method Investments

$ 65,867

Income (Loss) from Equity Method Investments

(52)

Equity Method Investment Summarized Financial Information Debt

$ 56,616

Debt Instrument, Interest Rate, Effective Percentage | Rate

7.04%

Debt Instrument Maturity Dates

Apr-23

HSRE, LLC [Member] [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

30.00%

Equity Method Investments

$ 13,761

Income (Loss) from Equity Method Investments

Equity Method Investment Summarized Financial Information Debt

$ 966

Debt Instrument, Interest Rate Terms

L+2.20%

Debt Instrument Maturity Dates

Jul-16

4040 Wilson Venture [Member]

Schedule of Equity Method Investments [Line Items]

Area Owned By Real Estate Venture Of Undeveloped Parcels Of Land | a

1.3

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 13,499

Income (Loss) from Equity Method Investments

Equity Method Investment Summarized Financial Information Debt

$ 0

Brandywine - Al Venture [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 46,406

Income (Loss) from Equity Method Investments

130

Equity Method Investment Summarized Financial Information Debt

$ 134,500

Debt Instrument, Interest Rate, Effective Percentage | Rate

3.92%

Debt Instrument Maturity Dates

^[2]

(b)

Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 17,262

Income (Loss) from Equity Method Investments

(434)

Equity Method Investment Summarized Financial Information Debt

$ 230,600

Debt Instrument, Interest Rate, Effective Percentage | Rate

3.39%

Debt Instrument Maturity Dates

^[3]

(c)

BDN Beacon Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

20.00%

Equity Method Investments

$ 0

$ 17,000

Income (Loss) from Equity Method Investments

907

Equity Method Investment Summarized Financial Information Debt

$ 0

TB-BDN Plymouth Apartments [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 12,402

Income (Loss) from Equity Method Investments

Equity Method Investment Summarized Financial Information Debt

$ 0

Debt Instrument, Interest Rate Terms

L+1.70%

Debt Instrument Maturity Dates

Dec-17

Six Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[4]

63.00%

Equity Method Investments

$ 0

Income (Loss) from Equity Method Investments

165

Equity Method Investment Summarized Financial Information Debt

$ 0

One Commerce Square [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[5]

25.00%

Equity Method Investments

$ 0

Income (Loss) from Equity Method Investments

933

Equity Method Investment Summarized Financial Information Debt

$ 0

Two Commerce Square [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[6]

25.00%

Equity Method Investments

$ 0

Income (Loss) from Equity Method Investments

614

Equity Method Investment Summarized Financial Information Debt

$ 0

Brandywine Nineteen Nineteen Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 6,214

Income (Loss) from Equity Method Investments

Equity Method Investment Summarized Financial Information Debt

$ 0

One Thousand Chesterbrook Blvd. [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 2,064

Income (Loss) from Equity Method Investments

461

Equity Method Investment Summarized Financial Information Debt

$ 24,861

Debt Instrument, Interest Rate, Effective Percentage | Rate

4.75%

Debt Instrument Maturity Dates

Dec-21

Four Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

65.00%

Equity Method Investments

$ 1,617

Income (Loss) from Equity Method Investments

320

Equity Method Investment Summarized Financial Information Debt

$ 10,535

Debt Instrument, Interest Rate, Effective Percentage | Rate

5.20%

Debt Instrument Maturity Dates

Feb-21

Residence Inn Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ 742

Income (Loss) from Equity Method Investments

326

Equity Method Investment Summarized Financial Information Debt

$ 13,700

Debt Instrument, Interest Rate, Effective Percentage | Rate

5.63%

Debt Instrument Maturity Dates

Feb-16

PJP VII [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

25.00%

Equity Method Investments

$ 783

Income (Loss) from Equity Method Investments

239

Equity Method Investment Summarized Financial Information Debt

$ 6,250

Debt Instrument, Interest Rate Terms

L+2.65%

Debt Instrument Maturity Dates

Dec-19

PJP Two [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

30.00%

Equity Method Investments

$ 330

Income (Loss) from Equity Method Investments

(87)

Equity Method Investment Summarized Financial Information Debt

$ 3,765

Debt Instrument, Interest Rate, Effective Percentage | Rate

6.12%

Debt Instrument Maturity Dates

Nov-23

G&I Interchange Office LLC (DRA — N. PA) [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[1],[5]

20.00%

Equity Method Investments

$ 0

Income (Loss) from Equity Method Investments

(619)

Equity Method Investment Summarized Financial Information Debt

$ 177,207

Debt Instrument, Interest Rate, Effective Percentage | Rate

5.78%

Debt Instrument Maturity Dates

Jan-15

Sale of ownership in properties | Rate

^[5]

80.00%

Seven Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

20.00%

Equity Method Investments

$ 447

Income (Loss) from Equity Method Investments

Equity Method Investment Summarized Financial Information Debt

$ 11,035

Debt Instrument, Interest Rate, Effective Percentage | Rate

4.22%

Debt Instrument Maturity Dates

^[7]

(d)

PJP Five [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

25.00%

Equity Method Investments

$ 175

Income (Loss) from Equity Method Investments

158

Equity Method Investment Summarized Financial Information Debt

$ 5,437

Debt Instrument, Interest Rate, Effective Percentage | Rate

6.47%

Debt Instrument Maturity Dates

Aug-19

Two Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

^[8]

35.00%

Equity Method Investments

$ 0

$ (100)

Income (Loss) from Equity Method Investments

265

Equity Method Investment Summarized Financial Information Debt

$ 0

PJP Six [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

25.00%

Equity Method Investments

$ 112

Income (Loss) from Equity Method Investments

Equity Method Investment Summarized Financial Information Debt

$ 8,404

Debt Instrument, Interest Rate, Effective Percentage | Rate

6.08%

Debt Instrument Maturity Dates

Apr-23

Coppell Associates [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

50.00%

Equity Method Investments

$ (1,169)

Income (Loss) from Equity Method Investments

(78)

Equity Method Investment Summarized Financial Information Debt

$ 15,984

Debt Instrument, Interest Rate, Effective Percentage | Rate

5.75%

Debt Instrument Maturity Dates

Feb-16

Eight Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investments

$ 0

Income (Loss) from Equity Method Investments

Invesco, L.P. [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investments

Income (Loss) from Equity Method Investments

$ 338

Secured Debt [Member]

Schedule of Equity Method Investments [Line Items]

Long-term Debt, Weighted Average Interest Rate

5.73%

6.65%

6.72%

Secured Debt [Member] | Brandywine - Al Venture [Member]

Schedule of Equity Method Investments [Line Items]

Long-term Debt, Weighted Average Interest Rate

^[2]

3.92%

Secured Debt [Member] | Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Long-term Debt, Weighted Average Interest Rate

^[3]

3.39%

Secured Debt [Member] | Seven Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Long-term Debt, Weighted Average Interest Rate

^[5]

4.22%

Secured Debt [Member] | Fixed rate loan maturing January 2019 [Member] | Brandywine - Al Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Face Amount

^[2]

$ 40,000

Debt Instrument, Interest Rate, Stated Percentage

^[2]

4.40%

Secured Debt [Member] | Fixed rate loan maturing January 2022 [Member] | Brandywine - Al Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Face Amount

^[4]

$ 28,000

Debt Instrument, Interest Rate, Stated Percentage

^[2]

4.65%

Secured Debt [Member] | Fixed rate loan maturing August 2019 [Member] | Brandywine - Al Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Face Amount

^[2]

$ 66,500

Debt Instrument, Interest Rate, Stated Percentage

^[2]

3.22%

Secured Debt [Member] | First mortgage - swapped to fixed [Member] | Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Face Amount

^[3]

$ 34,000

Debt Instrument, Interest Rate, Stated Percentage

^[3]

3.52%

Secured Debt [Member] | Second mortgage - swapped to fixed [Member] | Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Face Amount

^[3]

$ 56,000

Debt Instrument, Interest Rate, Stated Percentage

^[3]

3.19%

Secured Debt [Member] | Third mortgage - swapped to fixed [Member] | Austin Joint Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Face Amount

^[3]

$ 140,600

Debt Instrument, Interest Rate, Stated Percentage

^[3]

3.44%

Secured Debt [Member] | Mortgage Maturing February 2015 [Domain] | Brandywine - Al Venture [Member]

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Number of Fixed Rate Mortgages | Fixed_Rate_Mortgages

^[5]

Secured Debt [Member] | Mortgage Maturing February 2015 [Domain] | Seven Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment Summarized Financial Information Debt

^[5]

$ 8,000

Debt Instrument, Number of Fixed Rate Mortgages | Fixed_Rate_Mortgages

^[5]

Debt Instrument, Interest Rate, Stated Percentage

^[5]

6.00%

Debt Instrument, Interest Rate Increase

^[5]

1.00%

Secured Debt [Member] | Fixed Rate Loan Maturing September 2025 [Member] | Seven Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment Summarized Financial Information Debt

^[5]

$ 1,000

Debt Instrument, Interest Rate, Stated Percentage

^[5]

3.00%

Secured Debt [Member] | Fixed Rate Loan Maturing February 2014 [Member] | Seven Tower Bridge [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment Summarized Financial Information Debt

^[5]

$ 2,000

Debt Instrument, Interest Rate, Stated Percentage

^[5]

4.00%

[1]	(f)The basis differences associated with these ventures are allocated between cost and the underlying equity in the net assets of the investee and is accounted for as if the entity were consolidated (i.e., allocated to the Company’s relative share of assets and liabilities with an adjustment to recognize equity in earnings for the appropriate depreciation/amortization).
[2]	(b)The debt for these properties is comprised of three fixed rate mortgages: (1) $40.0 million with a 4.40% fixed interest rate due January 1, 2019, (2) $28.0 million with a 4.65% fixed interest rate due January 1, 2022, and (3) $66.5 million with a 3.22% fixed interest rate due August 1, 2019, resulting in a time and dollar weighted average rate of 3.92%.
[3]	(c)The debt for these properties is comprised of three mortgages: (1) $34.0 million with a 3.52% interest rate due November 1, 2018, (2) $56.0 million with a 3.19% interest rate due October 15, 2018, and (3) $140.6 million with a rate of 3.44% fixed interest rate due November 1, 2018, resulting in a time and dollar weighted average rate of 3.39%.
[4]	(g)On June 19, 2013, we acquired ownership of Six Tower Bridge. Real estate venture income reflects our previous partnership interest for the year to date period through June 18, 2013.
[5]	(e)Proceeds received by the Company from the sale of an 80% ownership stake in the properties exceeded the historical cost of those properties. No investment in the real estate venture was reflected on the balance sheet at formation.
[6]	(h)On December 19, 2013, we increased our ownership interest in One and Two Commerce Square. The real estate venture income reflects our previous partnership interest for the year to date period through December 18, 2013.
[7]	(d)Comprised of two fixed rate mortgages totaling $8.0 million that mature on February 8, 2015 and accrue interest at a current rate of 6% (increasing by 1% annually through maturity), a $1.0 million 3% fixed rate loan with interest only through its September 1, 2025 maturity, and a $2.0 million 4% fixed rate loan with interest only through its February 7, 2016 maturity, resulting in a time and dollar weighted average rate of 4.22%.
[8]	(i)The ownership interest in these properties was disposed of prior to December 31, 2013. For further information on BDN Beacon LLC, see the section entitled BDN Beacon Venture below. For further information on Two Tower Bridge, see the section entitled Two and Six Tower Bridge Exchange Transaction below.

Investment in Unconsolidated Ventures Aggregate Principal Payments of Recourse and Non-recourse Debt Payable to Third-parties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity Method Investments and Joint Ventures [Abstract]
Loss on real estate venture formation	$ 0	$ (950)	$ (222)
Schedule of Equity Method Investments [Line Items]
2014	232,375
2015	409,654
2016	467,705
2017	330,323
2018	336,954
Thereafter	822,454
Equity Method Investment Summarized Financial Information Debt	699,860
Equity Method Investments [Member]
Schedule of Equity Method Investments [Line Items]
2014	11,940
2015	191,304
2016	42,180
2017	13,937
2018	229,780
Thereafter	210,719
Equity Method Investment Summarized Financial Information Debt	$ 699,860

Deferred Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Components of Deferred Costs Net [Abstract]
Leasing Costs, Total Cost	$ 155,885	$ 150,331
Financing Costs, Total Cost	40,317	40,246
Total Cost	196,202	190,577
Leasing Costs, Accumulated Amortization	(58,805)	(58,343)
Financing Costs, Accumulated Amortization	(14,443)	(9,991)
Total, Accumulated Amortization	(73,248)	(68,334)
Leasing Costs, Deferred Costs, net	97,080	91,988
Financing Costs, Deferred Costs, net	25,874	30,255
Deferred Costs	$ 122,954	$ 122,243

Deferred Costs (Details Textuals) - USD ($) $ in Millions	12 Months Ended
Deferred Costs (Details Textuals) - USD ($) $ in Millions	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Costs (Textuals) [Abstract]
Capitalized internal direct leasing costs	$ 7.5	$ 7.5	$ 6.6

Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Intangible assets
Total Cost	$ 196,147	$ 152,611
Accumulated Amortization	(63,818)	(81,991)
Intangible Assets, net	132,329	70,620
In-place lease value [Member]
Intangible assets
Total Cost	150,782	87,909
Accumulated Amortization	(35,607)	(42,894)
Intangible Assets, net	115,175	45,015
Tenant relationship value [Member]
Intangible assets
Total Cost	38,692	56,137
Accumulated Amortization	(26,868)	(37,389)
Intangible Assets, net	11,824	18,748
Above market leases acquired [Member]
Intangible assets
Total Cost	6,673	8,565
Accumulated Amortization	(1,343)	(1,708)
Intangible Assets, net	5,330	6,857
Below market leases acquired [Member]
Intangible assets
Total Cost	81,991	77,083
Accumulated Amortization	(47,547)	(43,224)
Intangible Assets, net	$ 34,444	$ 33,859

Intangible Assets (Details 1) - USD ($) $ in Thousands	12 Months Ended
Intangible Assets (Details 1) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Annual amortization of intangible assets and liabilities
Intangible Assets, net	$ 132,329	$ 70,620
Assets [Member]
Annual amortization of intangible assets and liabilities
2014	27,043
2015	23,314
2016	18,573
2017	16,573
2018	12,161
Thereafter	34,665
Intangible Assets, net	132,329
Liabilities [Member]
Annual amortization of intangible assets and liabilities
2014	7,614
2015	5,455
2016	3,486
2017	2,890
2018	2,353
Thereafter	12,646
Intangible Assets, net	34,444
Tenant Move-Outs Prior to End of the Lease Term [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets Written Off Through Accelerated Amortization	$ 1,600	$ 1,400	$ 7,400
Intangible Liabilities Written Off Through Accelerated Amortization			$ 200

Debt Obligations (Consolidated Debt Obligations Outstanding) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Consolidated debt obligations

Plus: premiums/(discounts), net

$ (4,084)

Total mortgage indebtedness

670,151

$ 442,974

Total Debt Obligations

2,595,381

2,465,330

Repayments of Unsecured Debt

190,485

$ 145,500

Long Term Debt Maturities Repayments Of Principal

2,599,465

Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

669,762

443,942

Plus: premiums/(discounts), net

389

(968)

Total mortgage indebtedness

670,151

442,974

Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

1,929,703

2,027,953

Plus: premiums/(discounts), net

(4,473)

(5,597)

Total unsecured indebtedness

1,925,230

2,022,356

New Revolving Credit Facility [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 0

69,000

Debt Instrument, Interest Rate Terms

LIBOR + 1.50%

Debt Instrument Maturity Dates

Feb-16

Debt instrument, basis spread on variable rate

1.50%

Debt Instrument, Term

4 years

Option to extend Term Loan

1 year

Three-Year Term Loan - Swapped to fixed [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 150,000

150,000

Effective interest rate

2.60%

Debt Instrument Maturity Dates

Feb-15

Debt instrument, basis spread on variable rate

1.75%

Debt Instrument, Term

3 years

Option to extend Term Loan

1 year

Debt Instrument, Face Amount

$ 150,000

Four-Year Term Loan - Variable [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 100,000

100,000

Debt Instrument, Interest Rate Terms

LIBOR + 1.75%

Debt Instrument Maturity Dates

Feb-16

Debt instrument, basis spread on variable rate

1.75%

Debt Instrument, Term

4 years

Option to extend Term Loan

1 year

Debt Instrument, Face Amount

$ 100,000

Seven Year Term Loan - Swapped to fixed [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 200,000

200,000

Effective interest rate

3.62%

Debt Instrument Maturity Dates

Feb-19

Debt instrument, basis spread on variable rate

1.90%

Debt Instrument, Term

7 years

Debt Instrument, Face Amount

$ 200,000

$300.0M 5.750% Guaranteed Notes due 2012 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Debt instrument stated interest rate

5.75%

Debt Instrument, Face Amount

$ 300,000

$250.0M 5.400% Guaranteed Notes due 2014 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 218,549

238,379

Effective interest rate

5.53%

Debt Instrument Maturity Dates

Nov-14

Debt instrument stated interest rate

5.40%

Debt Instrument, Face Amount

$ 250,000

$250.0M 7.500% Guaranteed Notes due 2015 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 157,625

166,535

Effective interest rate

7.76%

Debt Instrument Maturity Dates

May-15

Debt instrument stated interest rate

7.50%

Debt Instrument, Face Amount

$ 250,000

$250.0M 6.000% Guaranteed Notes due 2016 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 149,919

150,429

Effective interest rate

5.95%

Debt Instrument Maturity Dates

Apr-16

Debt instrument stated interest rate

6.00%

Debt Instrument, Face Amount

$ 250,000

$300.0M 5.700% Guaranteed Notes due 2017 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 300,000

300,000

Effective interest rate

5.68%

Debt Instrument Maturity Dates

May-17

Debt instrument stated interest rate

5.70%

Debt Instrument, Face Amount

$ 300,000

$325.0M 4.950% Guaranteed Notes due 2018 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 325,000

325,000

Effective interest rate

5.13%

Debt Instrument Maturity Dates

Apr-18

Debt instrument stated interest rate

4.95%

Debt Instrument, Face Amount

$ 325,000

Note 2023 [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 250,000

250,000

Effective interest rate

4.02%

Debt Instrument Maturity Dates

Feb-23

Indenture IA (Preferred Trust I) [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 27,062

27,062

Effective interest rate

2.75%

Debt Instrument Maturity Dates

Mar-35

Indenture IB (Preferred Trust I) [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 25,774

25,774

Effective interest rate

3.30%

Debt Instrument Maturity Dates

Apr-35

Indenture II (Preferred Trust II) [Member] | Unsecured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 25,774

25,774

Effective interest rate

3.09%

Debt Instrument Maturity Dates

Jul-35

Tysons Corner [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 91,395

93,188

Effective interest rate

5.36%

Debt Instrument Maturity Dates

Aug-15

One Commerce Square [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 125,089

Effective interest rate

^[1]

3.68%

Debt Instrument Maturity Dates

Jan-16

Two Logan Square [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 88,583

89,340

Effective interest rate

7.57%

Debt Instrument Maturity Dates

Apr-16

Fairview Eleven Tower [Member]

Participating Mortgage Loans [Line Items]

Equity Method Investment, Ownership Percentage

^[2]

50.00%

Fairview Eleven Tower [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 21,630

22,000

Effective interest rate

^[2]

4.25%

Debt Instrument Maturity Dates

Jan-17

Two Commerce Square [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 112,000

Effective interest rate

^[1]

4.51%

Debt Instrument Maturity Dates

Apr-23

IRS Philadelphia Campus [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 190,964

197,111

Effective interest rate

7.00%

Debt Instrument Maturity Dates

Sep-30

Cira South Garage [Member] | Secured Debt [Member]

Consolidated debt obligations

Long-term Debt, Gross

$ 40,101

$ 42,303

Effective interest rate

7.12%

Debt Instrument Maturity Dates

Sep-30

[1]	This loan was assumed upon acquisition of the related properties on December 19, 2013. The interest rate reflects the market rate at the time of acquisition.
[2]	(b)Represents the full debt amount of a property in a consolidated joint venture for which the Company maintains a 50% interest.

Debt Obligations (Outstanding Unsecured Notes in Series of Transactions) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2013 USD ($)
Schedule of principal payments of debt obligations
Repurchase Amount	$ 31,296
Principal	29,250
Loss	(2,119)
Deferred Financing Amortization	40
Note Four [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	20,822
Principal	19,830
Loss	(1,020)
Deferred Financing Amortization	16
Note Five [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	9,902
Principal	8,910
Loss	(1,036)
Deferred Financing Amortization	23
Note Six [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	572
Principal	510
Loss	(63)
Deferred Financing Amortization	$ 1
2012 5.750% Notes [Member]
Schedule of principal payments of debt obligations
Debt instrument stated interest rate	5.75%
2014 5.400% Notes
Schedule of principal payments of debt obligations
Debt instrument stated interest rate	5.40%
2015 7.500% Notes [Member]
Schedule of principal payments of debt obligations
Debt instrument stated interest rate	7.50%

Debt Obligations (Aggregate Scheduled Principal Payments of Debt Obligation, Excluding Amortization of Discounts and Premiums) (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Summary of debt repurchases
2014	$ 232,375
2015	409,654
2016	467,705
2017	330,323
2018	336,954
Thereafter	822,454
Total principal payments	2,599,465
Net unamortized premiums/(discounts)	(4,084)
Total Debt Obligations	$ 2,595,381	$ 2,465,330

Debt Obligations (Details Textuals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt obligations (Textuals)
Amortization of Financing Costs	$ 4,676	$ 6,208	$ 4,991
Early Repayment of Senior Debt	31,296
Gain (loss) on early extinguishment of debt	(2,119)	(22,002)	$ (2,776)
Unsecured Debt [Member]
Debt obligations (Textuals)
Long-term Debt, Gross	1,929,703	2,027,953
Secured Debt [Member]
Participating Mortgage Loans [Line Items]
Properties encumbered mortgage indebtedness carrying value, net	669,762	591,300
Debt obligations (Textuals)
Long-term Debt, Gross	669,762	443,942
Letter of Credit [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Letters of credit outstanding	$ 1,300
New Revolving Credit Facility [Member] \| Unsecured Debt [Member]
Participating Mortgage Loans [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Debt obligations (Textuals)
Unused availability under the Credit Facility	$ 598,700
Option for additional borrowings subject to customary conditions and limitations	200,000
Long-term Debt, Gross	0	69,000
Note 2023 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Long-term Debt, Gross	250,000	250,000
$300.0M 5.750% Guaranteed Notes due 2012 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	5.75%
$250.0M 5.400% Guaranteed Notes due 2014 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	5.40%
Long-term Debt, Gross	$ 218,549	238,379
$250.0M 7.500% Guaranteed Notes due 2015 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	7.50%
Long-term Debt, Gross	$ 157,625	166,535
$250.0M 6.000% Guaranteed Notes due 2016 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Long-term Debt, Gross	$ 149,919	150,429
$300.0M 5.700% Guaranteed Notes due 2017 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	5.70%
Long-term Debt, Gross	$ 300,000	300,000
$325.0M 4.950% Guaranteed Notes due 2018 [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 325,000
Debt Instrument, Interest Rate, Stated Percentage	4.95%
Long-term Debt, Gross	$ 325,000	325,000
Three Year Term Loan [Member] \| Unsecured Debt [Member]
Participating Mortgage Loans [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Debt obligations (Textuals)
Debt instrument, face amount	$ 150,000
Derivative, Average Fixed Interest Rate	2.596%
Long-term Debt, Gross	$ 150,000	150,000
Seven Year Term Loan [Member] \| Unsecured Debt [Member]
Participating Mortgage Loans [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
Debt obligations (Textuals)
Debt instrument, face amount	$ 200,000
Derivative, Average Fixed Interest Rate	3.623%
Long-term Debt, Gross	$ 200,000	$ 200,000
Note Nine [Member] \| Unsecured Debt [Member]
Debt obligations (Textuals)
Debt instrument, face amount	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Federal Funds Rate [Member] \| Bank Term Loan and the Credit Facility [Member]
Participating Mortgage Loans [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%

Debt Obligations (Details Textuals 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Line of Credit	$ 0	$ 69,000
Long Term Debt Maturities Repayments Of Principal	2,599,465
Extinguishment of Debt, Amount	29,250
Amortization of Financing Costs	4,676	6,208	$ 4,991
Derivative, Gain (Loss) on Derivative, Net	$ 0	$ (2,985)	$ 0
Bank Term Loan And The Credit Facility [Member] \| Federal Funds Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Interest Rate During Period	0.29%	1.02%
Long-term Debt, Gross	$ 1,929,703	$ 2,027,953
Unsecured Debt [Member] \| Three Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Derivative, Average Fixed Interest Rate	2.596%
Long-term Debt, Gross	$ 150,000	150,000
Unsecured Debt [Member] \| Four-Year Term Loan - Variable [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Long-term Debt, Gross	$ 100,000	100,000
Unsecured Debt [Member] \| Seven Year Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
Declining prepayment penalty in year three	1.00%
Derivative, Average Fixed Interest Rate	3.623%
Long-term Debt, Gross	$ 200,000	200,000
Unsecured Debt [Member] \| Three and Four Year Term Loan [Member]
Debt Instrument [Line Items]
Derivative, lower remaining maturity range	3 years
Derivative, higher remaining maturity range	5 years
Unsecured Debt [Member] \| Note 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 250,000	250,000
Unsecured Debt [Member] \| Note Five [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	157,625	166,535
Unsecured Debt [Member] \| Note Six [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	149,919	150,429
Unsecured Debt [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount	$ 1,300
Unsecured Debt [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Long-term Debt, Gross	$ 0	$ 69,000
Line of Credit Facility, Remaining Borrowing Capacity	598,700
Line of Credit Facility, Option for Additional Borrowing Capacity subject to customary conditions and limitations	$ 200,000
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate	5.73%	6.65%	6.72%
Long-term Debt, Gross	$ 669,762	$ 443,942
Note Six [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount	$ 510

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Company's estimates of fair value differ from the carrying amounts
Mortgage notes payable, Carrying Amount	$ 669,762	$ 443,942
Mortgage notes payable, Fair Value	715,244	486,412
Unsecured notes payable, Carrying Amount	1,401,093	1,430,343
Unsecured notes payable, Fair Value	1,471,041	1,553,123
Variable rate debt instruments, Carrying Amount	528,610	597,610
Variable rate debt instruments, Fair Value	526,693	595,693
Notes receivable, Carrying Amount	7,026	7,226
Notes receivable, Fair Value	$ 7,759	$ 7,783

Fair Value of Financial Instruments (Details Textuals)	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Weighted Average Fair Value Interest Rate on Debt	4.534%

Risk Management and Use of Financial Instruments (Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Long Term Debt Maturities Repayments Of Principal	$ 2,599,465
Derivative, Gain (Loss) on Derivative, Net	0	$ (2,985)	$ 0
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	51,548	51,548
Fair value	767	(2,391)
Other Assets [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.300% Interest Rate Swap Maturing January 30, 2021 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 25,774	25,774
Derivative, Fixed Interest Rate	3.30%
Fair value	$ 549	(1,262)
Other Assets [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.090% Interest Rate Swap Maturing October 30, 2019 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 25,774	25,774
Derivative, Fixed Interest Rate	3.09%
Fair value	$ 218	(1,129)
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	377,062	377,062
Fair value	(2,188)	(11,819)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.623% Interest Rate Swap Maturing February 1, 2019 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 200,000	200,000
Derivative, Fixed Interest Rate	3.623%
Fair value	$ (545)	(8,859)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 2.703% Interest Rate Swap Maturing February 1, 2016 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 77,000	77,000
Derivative, Fixed Interest Rate	2.703%
Fair value	$ (887)	(1,343)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 2.470% Interest Rate Swap Maturing February 1, 2015 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 50,000	50,000
Derivative, Fixed Interest Rate	2.47%
Fair value	$ (283)	(458)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 2.513% Interest Rate Swap Maturing May 1, 2015 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 23,000	23,000
Derivative, Fixed Interest Rate	2.513%
Fair value	$ (162)	(245)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 2.750% Interest Rate Swap Maturing September 30, 2017 [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 27,062	27,062
Derivative, Fixed Interest Rate	2.75%
Fair value	$ (311)	$ (914)

Discontinued Operations (Details) $ in Thousands, ft² in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2013 USD ($) ft²	Sep. 30, 2013 USD ($)	Jun. 30, 2013 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2012 USD ($)	Jun. 30, 2012 USD ($)	Mar. 31, 2012 USD ($)	Dec. 31, 2013 USD ($) ft²	Dec. 31, 2012 USD ($) Properties	Dec. 31, 2011 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations									$ 4,207	$ 43,838	$ 19,841
Revenue:
Rents									461,387	437,560	441,329
Tenant Reimbursements									79,087	77,060	77,404
Termination Fees									4,497	3,233	2,951
Other									4,186	5,710	5,348
Total revenue	$ 138,658	$ 143,354	$ 140,644	$ 139,554	$ 136,395	$ 134,238	$ 131,530	$ 133,516	562,210	535,679	538,568
Expenses:
Property operating expenses									160,406	152,319	159,768
Real estate taxes									55,612	53,402	51,433
Depreciation and amortization									197,021	188,382	202,933
Total operating expenses									446,418	424,643	444,326
Investment Income, Interest									1,044	3,008	1,810
Income from discontinued operations before gain on sale of interests in real estate									825	9,064	12,794
Net gain (loss) on disposition of discontinued operations									3,382	34,774	7,047
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations									4,207	43,838	19,841
Revenue:
Rents									4,754	28,678	43,050
Tenant Reimbursements									355	2,353	5,030
Termination Fees									0	11	75
Other									123	378	110
Total revenue									5,232	31,420	48,265
Expenses:
Property operating expenses									1,839	8,687	13,940
Real estate taxes									649	3,468	5,356
Depreciation and amortization									1,921	10,208	16,178
Total operating expenses									4,409	22,363	35,474
Investment Income, Interest									2	7	3
Income from discontinued operations before gain on sale of interests in real estate									825	9,064	12,794
Net gain (loss) on disposition of discontinued operations									$ 3,382	$ 34,774	$ 7,047
Net Rentable Space Sold \| ft²	2.3								2.3
Number of properties sold (in properties) \| Properties										32

Non Controlling Interests in The Parent Company Non Contolling Interests in the Parent Company (Details) - USD ($) $ in Millions	Dec. 31, 2013	Dec. 31, 2012
Noncontrolling Interest [Abstract]
Aggregate amount related to non-controlling interests classified within equity	$ 20.3	$ 21.2
Settlement value of non controlling interest in operating partnership	$ 24.8	$ 22.5

Beneficiaries Equity of The Parent Company (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Preferred Units [Line Items]
Preferred shares, dividend rate (as a percent)									6.90%
Numerator
Income (loss) from continuing operations, Basic									$ 38,982	$ (37,309)	$ (24,556)
Income (loss) from continuing operations, Diluted									38,982	(37,309)	(24,556)
Net income (loss) from continuing operations attributable to non-controlling interests, Basic									(357)	863	994
Net income (loss) from continuing operations attributable to non-controlling interests, Diluted									(357)	863	994
Amount allocated to unvested restricted shareholders/unitholders, Basic									(363)	(376)	(505)
Amount allocable to unvested restricted shareholders, Diluted									(363)	(376)	(505)
Preferred share/unit dividends, Basic									(6,900)	(10,405)	(7,992)
Preferred share/unit dividends, Diluted									(6,900)	(10,405)	(7,992)
Preferred share/unit redemption premium, basic									0	(4,052)	0
Preferred share/unit redemption Premium, Diluted									0	(4,052)	0
Income Loss from continuing operations available to common shareholders/unitholders, Basic									31,362	(51,279)	(32,059)
Income (loss) from continuing operations available to common unit holders, Diluted									31,362	(51,279)	(32,059)
Discontinued operations attributable to common unitholders									4,207	43,838	19,841
Income (loss) from discontinued operations, Diluted									4,207	43,838	19,841
Discontinued operations attributable to non-controlling interests - LP units									(55)	(797)	(778)
Discontinued operations attributable to non-controlling interests, diluted									(55)	(797)	(778)
Discontinued operations attributable to common shareholders, Basic									4,152	43,041	19,063
Discontinued operations attributable to common shareholders, Diluted									4,152	43,041	19,063
Net income (loss) attributable to Common Shareholders/Unitholders									35,514	(8,238)	(12,996)
Net income (loss) available to common shareholders/unitholders, Diluted									$ 35,514	$ (8,238)	$ (12,996)
Denominator
Weighted-average shares/units outstanding, Basic									153,140,458	143,257,097	135,444,424
Contingent securities/Stock based compensation									1,273,853	0	0
Weighted-average shares/units outstanding, Diluted									154,414,311	143,257,097	135,444,424
Earnings per Common Share:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ 0.20	$ (0.36)	$ (0.24)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									0.20	(0.36)	(0.24)
Discontinued operations attributable to common shareholders/unitholders, Basic									0.03	0.30	0.14
Discontinued operations attributable to common shareholders, Diluted									0.03	0.30	0.14
Net income (loss) attributable to common shareholders/unitholders, Basic	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	0.23	(0.06)	(0.10)
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ 0.23	$ (0.06)	$ (0.10)

Beneficiaries Equity of The Parent Company (DetailsTextuals) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Jan. 15, 2014	Dec. 10, 2013	Apr. 10, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 05, 2013
Class of Stock [Line Items]
Stock Redeemed or Called During Period, Value					$ (103,448)
Net Proceeds from Issuance of Preferred Stock and Preference Stock				$ 0	$ 96,237	$ 0
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Distributions Declared, Per Share				$ 0.60	$ 0.60	$ 0.60
Preferred Stock, Shares Issued				4,000,000	4,000,000
Issuance of Common Shares of Beneficial Interest, shares			12,650,000
Issuance of Common Shares of Beneficial Interest				$ 182,034	$ 96,850	$ 8,272
Additional shares Expected to be purchased under program				539,200
Dividends paid for preferred shares				$ 6,900	10,405	7,992
Additional shares granted under option to purchase in public offering			1,650,000
Proceeds from Issuance of Common Stock			$ 181,500	$ 181,527	0	7,930
Percentage of Preferential return				6.90%
Dividends Payable, Amount				$ 25,584	23,652
Redemption Premium				$ 0	$ 4,052	$ 0
Dividend Declared [Member]
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Distributions Declared, Per Share		$ 0.15
Dividend Paid
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Dividends Payable, Amount		$ 23,900
Series E Preferred Stock [Member]
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Dividends paid for preferred shares	$ 1,700
Percentage of Preferential return				6.90%
Preferred Stock, Liquidation Preference Per Share				$ 25.00
Class A Units [Member]
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Antidilutive securities excluded from computation of earnings per share				1,763,739	1,845,737	2,698,647
Offering Program [Member]
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Shares authorized for Equity Offering Program							16,000,000
Remaining shares available for sales							16,000,000
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Stock Redeemed or Called During Period, Value					$ (43)
Stock Redeemed or Called During Period, Shares					(4,300,000)
Beneficiaries Equity of The Parent Company (Textuals) [Abstract]
Issuance of Common Shares of Beneficial Interest, shares					4,000,000
Issuance of Common Shares of Beneficial Interest					$ 40

Partners Equity of The Operating Partnership (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator
Income (loss) from continuing operations, Basic									$ 38,982	$ (37,309)	$ (24,556)
Income (loss) from continuing operations, Diluted									38,982	(37,309)	(24,556)
Amount allocated to unvested restricted shareholders/unitholders, Basic									(363)	(376)	(505)
Amount allocable to unvested restricted unitholders, Diluted									(363)	(376)	(505)
Preferred share/unit dividends, Basic									(6,900)	(10,405)	(7,992)
Preferred share/unit dividends, Diluted									(6,900)	(10,405)	(7,992)
Redemption Premium									0	4,052	0
Preferred share/unit redemption Premium, Diluted									0	(4,052)	0
Income Loss from continuing operations available to common shareholders/unitholders, Basic									31,362	(51,279)	(32,059)
Income (loss) from continuing operations available to common unit holders, Diluted									31,362	(51,279)	(32,059)
Discontinued operations attributable to common unitholders									4,207	43,838	19,841
Net income (loss) attributable to Common Shareholders/Unitholders									35,514	(8,238)	(12,996)
Net income (loss) available to common shareholders/unitholders, Diluted									$ 35,514	$ (8,238)	$ (12,996)
Denominator
Weighted-average shares/units outstanding, Basic									153,140,458	143,257,097	135,444,424
Contingent securities/Stock based compensation									1,273,853	0	0
Weighted-average shares/units outstanding, Diluted									154,414,311	143,257,097	135,444,424
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ 0.20	$ (0.36)	$ (0.24)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									0.20	(0.36)	(0.24)
Discontinued operations attributable to common shareholders/unitholders, Basic									0.03	0.30	0.14
Discontinued operations attributable to common shareholders, Diluted									0.03	0.30	0.14
Net income (loss) attributable to common shareholders/unitholders, Basic	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	0.23	(0.06)	(0.10)
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ 0.23	$ (0.06)	$ (0.10)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Income (loss) from continuing operations, Basic									$ 38,982	$ (37,309)	$ (24,556)
Income (loss) from continuing operations, Diluted									38,982	(37,309)	(24,556)
Amount allocated to unvested restricted shareholders/unitholders, Basic									(363)	(376)	(505)
Amount allocable to unvested restricted unitholders, Diluted									(363)	(376)	(505)
Preferred share/unit dividends, Basic									(6,900)	(10,405)	(7,992)
Preferred share/unit dividends, Diluted									(6,900)	(10,405)	(7,992)
Redemption Premium									0	4,052	0
Preferred share/unit redemption Premium, Diluted									0	(4,052)	0
Income Loss from continuing operations available to common shareholders/unitholders, Basic									31,719	(52,142)	(33,053)
Income (loss) from continuing operations available to common unit holders, Diluted									31,719	(52,142)	(33,053)
Discontinued operations attributable to common unitholders									4,207	43,838	19,841
Discontinued operations attributable to common unitholders, Diluted									4,207	43,838	19,841
Net income (loss) attributable to Common Shareholders/Unitholders									35,926	(8,304)	(13,212)
Net income (loss) available to common shareholders/unitholders, Diluted									$ 35,926	$ (8,304)	$ (13,212)
Denominator
Weighted-average shares/units outstanding, Basic									154,929,545	145,883,217	145,118,841
Contingent securities/Stock based compensation									1,273,853	0	0
Weighted-average shares/units outstanding, Diluted									156,203,398	145,883,217	145,118,841
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ 0.20	$ (0.36)	$ (0.23)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									0.20	(0.36)	(0.23)
Discontinued operations attributable to common shareholders/unitholders, Basic									0.03	0.30	0.14
Discontinued operations attributable to common shareholders, Diluted									0.03	0.30	0.14
Net income (loss) attributable to common shareholders/unitholders, Basic									0.23	(0.06)	(0.09)
Net income (loss) attributable to common shareholders/unitholders, Diluted									$ 0.23	$ (0.06)	$ (0.09)

Partners Equity of The Operating Partnership (DetailsTextuals) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended								12 Months Ended
	Jan. 15, 2014	Jul. 15, 2013	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 10, 2013	Nov. 05, 2013
Earnings per Common Partnership Unit [Line Items]
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest											$ 38,982	$ (37,309)	$ (24,556)
Income Loss From Continuing Operations Including Portion Attributable To Non controlling Interest Diluted											38,982	(37,309)	(24,556)
Amount allocated to unvested restricted shareholders											363	376	505
Amount allocated to unvested restricted shareholders, Diluted											363	376	505
Preferred share/unit dividends, Basic											(6,900)	(10,405)	(7,992)
Preferred share/unit dividends, Diluted											(6,900)	(10,405)	(7,992)
Preferred share/unit redemption premium, basic											0	(4,052)	0
Preferred share/unit redemption Premium, Diluted											0	(4,052)	0
Income Loss from continuing operations available to common shareholders Basic											31,362	(51,279)	(32,059)
Income Loss from continuing operations available to common shareholders Diluted											31,362	(51,279)	(32,059)
Discontinued operations attributable to common unitholders											4,207	43,838	19,841
Net Income (Loss) Available to Common Stockholders, Basic											35,514	(8,238)	(12,996)
Net Income (Loss) Available to Common Stockholders, Diluted											$ 35,514	$ (8,238)	$ (12,996)
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements											1,273,853	0	0
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic											$ 0.20	$ (0.36)	$ (0.24)
Income (Loss) from Continuing Operations, Per Diluted Share											0.20	(0.36)	(0.24)
Discontinued operations attributable to common shareholders/unitholders, Basic											0.03	0.30	0.14
Discontinued operations attributable to common shareholders, Diluted											0.03	0.30	0.14
Net income (loss) attributable to common shareholders/unitholders, Basic			$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	0.23	(0.06)	(0.10)
Net income (loss) attributable to common shareholders/unitholders, Diluted			$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ 0.23	$ (0.06)	$ (0.10)
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Dividends Payable, Amount			$ 25,584				$ 23,652				$ 25,584	$ 23,652
Percentage of Preferential return											6.90%
Dividends, Preferred Stock, Cash											$ 6,900	10,405	$ 7,992
Partners' Capital Account, Redemptions												$ (9,741)
Weighted-average shares/units outstanding, Basic											153,140,458	143,257,097	135,444,424
Weighted-average shares/units outstanding, Diluted											154,414,311	143,257,097	135,444,424
Series E Preferred Stock [Member]
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Percentage of Preferential return											6.90%
Preferred Stock, Liquidation Preference Per Share			$ 25.00								$ 25.00
Dividends, Preferred Stock, Cash	$ 1,700
Class A Units [Member]
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Redeemable Limited Partnership Units Potential Cash Redemption Value Closing Market Price			$ 14.09				$ 12.19				$ 14.09	$ 12.19	$ 9.50
Limited Partners' Capital Account, Units Outstanding			1,763,739				1,845,737				1,763,739	1,845,737
Offering Program [Member]
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Shares Authorized For Equity Offering Program															16,000,000
Remaining Shares Available For Sales															16,000,000
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest											$ 38,982	$ (37,309)	$ (24,556)
Income Loss From Continuing Operations Including Portion Attributable To Non controlling Interest Diluted											38,982	(37,309)	(24,556)
Amount allocated to unvested restricted shareholders											363	376	505
Amount allocated to unvested restricted shareholders, Diluted											363	376	505
Preferred share/unit dividends, Basic											(6,900)	(10,405)	(7,992)
Preferred share/unit dividends, Diluted											(6,900)	(10,405)	(7,992)
Preferred share/unit redemption premium, basic											0	(4,052)	0
Preferred share/unit redemption Premium, Diluted											0	(4,052)	0
Income Loss from continuing operations available to common shareholders Basic											31,719	(52,142)	(33,053)
Income Loss from continuing operations available to common shareholders Diluted											31,719	(52,142)	(33,053)
Discontinued operations attributable to common unitholders											4,207	43,838	19,841
Discontinued operations attributable to common unitholders, Diluted											4,207	43,838	19,841
Net Income (Loss) Available to Common Stockholders, Basic											35,926	(8,304)	(13,212)
Net Income (Loss) Available to Common Stockholders, Diluted											$ 35,926	$ (8,304)	$ (13,212)
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements											1,273,853	0	0
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic											$ 0.20	$ (0.36)	$ (0.23)
Income (Loss) from Continuing Operations, Per Diluted Share											0.20	(0.36)	(0.23)
Discontinued operations attributable to common shareholders/unitholders, Basic											0.03	0.30	0.14
Discontinued operations attributable to common shareholders, Diluted											0.03	0.30	0.14
Net income (loss) attributable to common shareholders/unitholders, Basic											0.23	(0.06)	(0.09)
Net income (loss) attributable to common shareholders/unitholders, Diluted											$ 0.23	$ (0.06)	$ (0.09)
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Distribution Declared per common partnership unit														$ 0.15
Dividends Payable, Amount			$ 25,584				$ 23,652				$ 25,584	$ 23,652		$ 23,900
Percentage of Preferential return											6.90%		6.90%
Weighted-average shares/units outstanding, Basic											154,929,545	145,883,217	145,118,841
Weighted-average shares/units outstanding, Diluted											156,203,398	145,883,217	145,118,841
BRANDYWINE OPERATING PARTNERSHIP, L.P. \| 6.90% Series E-linked Preferred Units [Member]
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Percentage of Preferential return											6.90%
Preferred Stock, Liquidation Preference Per Share			$ 25.00								$ 25.00
Dividends, Preferred Stock, Cash		$ 1,700
General Partner [Member] \| BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Preferred share/unit redemption premium, basic												$ (4,052)
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Dividends, Preferred Stock, Cash											$ 6,900	10,405	$ 7,992
Partners' Capital Account, Redemptions											$ (17)	$ 9,741

Share Based and Deferred Compensation (Option Activity) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	2,799,140
Stock-based compensation expense	$ 8,300,000	$ 8,600,000	$ 6,400,000
Stock-based compensation expense, capitalized	1,400,000	$ 2,600,000	1,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 0
Option activity
Outstanding at beginning of year, shares	3,337,549
Exercised, shares	(236,318)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period	(117,662)
Outstanding at end of year, shares	2,983,569.000	3,337,549
Outstanding at beginning of year, Weighted Average Exercise Price	$ 14.85
Exercised, Weighted Average Exercise Price	9.86
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	18.61
Outstanding at end of year, Weighted Average Exercise Price	15.50	$ 14.85
Vested/Exercisable at end of period, Weighted Average Exercise Price	$ 15.74
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 1 month 25 days	5 years 11 months 13 days
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	5 years 20 days
Outstanding at beginning of year, Aggregate Intrinsic Value	$ 0
Outstanding at end of year, Aggregate Intrinsic Value	$ 0	$ 0
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	184,429
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 months 20 days
Stock-based compensation expense	$ 700,000	1,600,000	1,400,000
Stock-based compensation expense, capitalized	$ 100,000	$ 500,000	$ 400,000
Option activity
Outstanding at end of year, shares	2,983,569

Share Based and Deferred Compensation (Restricted Share Activity) (Details)	12 Months Ended
	Dec. 31, 2013 Age $ / shares shares	Dec. 31, 2012 $ / shares shares
Restricted Share Awards [Member]
Company's restricted share activity
Non-vested at January 1, 2012, shares	597,708
Non-vested at January 1, 2012, Weighted Average Grant Date Fair value \| $ / shares	$ 12.57
Granted, shares	182,576
Granted, Weighted Average Grant Date Fair value \| $ / shares	$ 13.13
Vested, shares	(208,306)
Vested, Weighted Average Grant Date Fair value \| $ / shares	$ 13.13
Forfeited, shares	(8,265)
Forfeited, Weighted Average Grant Date Fair Value \| $ / shares	$ 11.41
Non-vested at December 31, 2012, shares	563,713	597,708
Non-vested at December 31, 2012, Weighted Average Grant Date Fair value \| $ / shares	$ 12.56	$ 12.57
Restricted Performance Share Units Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Age limit of voluntary termination of employment \| Age	57
Company's restricted share activity
Vested, shares		(64,678)
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	15 years
Executive Officer [Member] \| Restricted Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Age limit of voluntary termination of employment	57
Company's restricted share activity
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	15 years

Share Based and Deferred Compensation (Details Textuals)	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2013 USD ($) Employees shares	Dec. 31, 2012 USD ($) shares	Sep. 30, 2011 USD ($)	Dec. 31, 2013 USD ($) Age Employees shares	Dec. 31, 2012 USD ($) shares	Dec. 31, 2011 USD ($)	Feb. 25, 2013 shares	Mar. 01, 2012 shares	Mar. 02, 2011 shares
Share Based and Deferred Compensation (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number \| shares	2,983,569.000	3,337,549		2,983,569.000	3,337,549
Stock-based compensation expense, capitalized				$ 1,400,000	$ 2,600,000	$ 1,500,000
Award vesting term, minimum				1 year
Award vesting term, maximum				10 years
Stock-based compensation expense				$ 8,300,000	8,600,000	6,400,000
Vesting Period, Minimum				3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period \| shares				236,318
Defined Contribution Plan, Employer Discretionary Contribution Amount				$ 400,000
Stock Option [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number \| shares	2,983,569			2,983,569
Unrecognized compensation expenses	$ 100,000			$ 100,000
Weighted average period over which options will be recognized				2 months 20 days
Stock-based compensation expense, capitalized				$ 100,000	500,000	400,000
Stock-based compensation expense				700,000	1,600,000	1,400,000
Restricted Share Awards [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Unrecognized compensation expenses	$ 1,900,000			$ 1,900,000
Weighted average period over which options will be recognized				1 year 1 month 21 days
Stock-based compensation expense, capitalized				$ 600,000	$ 900,000	700,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number \| shares	563,713	597,708		563,713	597,708
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				three to seven years from the initial grant date
Award vesting term, minimum				3 years
Award vesting term, maximum				7 years
Stock-based compensation expense				$ 3,200,000	$ 3,400,000	3,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Cliff Vesting, Minimum				3 years
Voluntary termination of employment terms				after reaching age 57 and accumulating at least 15 years of service with the Company
Accumulated Service Period For Voluntary Termination				15 years
Restricted Performance Share Units Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Stock-based compensation expense, capitalized	$ 800,000			$ 1,200,000		500,000
Stock-based compensation expense	$ 4,400,000	$ 1,700,000		$ 3,500,000
Vesting Period, Minimum				3 years
Voluntary termination of employment terms				after reaching age 57 and accumulating at least 15 years of service with the Company
Age limit of voluntary termination of employment \| Age				57
Accumulated Service Period For Voluntary Termination				15 years
Maximum percentage of the participant's base units				200.00%
Fair value of awards on the grant date			$ 2,000,000	$ 4,100,000	4,100,000
Number of executives with employment agreements \| Employees	2			2
Employee Share Purchase Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Stock-based compensation expense				$ 100,000	100,000	$ 100,000
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date				15.00%
Aggregate share-based awards awarded to executives \| shares	1,250,000			1,250,000
Stock Issued During Period, Value, Employee Stock Purchase Plan				$ 300,000	400,000
Share purchases made by employees under ESPP				85% of the average closing price per share for a specified period
Share purchases made by employees under ESPP, Percentage						85.00%
Percentage of plan contribution				20.00%
Amount of participant contribution	$ 50,000			$ 50,000
Deferred Compensation Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Deferred Compensation Arrangement With Individual Decrease In Compensation Expense				$ 200,000		$ 100,000
Deferred compensation arrangement with individual increase in compensation expense.					$ 300,000
Number of shares to be issued under deferred compensation plan included in total shares outstanding \| shares	300,000	300,000		300,000	300,000
Executive Officer [Member] \| Restricted Share Awards [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Aggregate share-based awards awarded to executives \| shares							157,208
Age limit of voluntary termination of employment				57
Executive Officer [Member] \| Restricted Performance Share Units Plan [Member]
Share Based and Deferred Compensation (Textuals) [Abstract]
Aggregate share-based awards awarded to executives \| shares							231,093	242,122	113,256

Share Based and Deferred Compensation 401(K) Plan (Details) $ in Millions	12 Months Ended
	Dec. 31, 2013 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent	100.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0.4

Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Dividends, Common Stock [Abstract]
Common Share Distributions Payments of Ordinary Dividends	$ 0.52	$ 0.39	$ 0.37
Common Share Distributions Capital Gain	0.00	0.00	0.00
Common Share Distributions Non-taxable Distributions	0.08	0.21	0.23
Common Stock, Dividends, Per Share, Declared	$ 0.60	$ 0.60	$ 0.60
Percentage Of Distributions classified as ordinary income	87.00%	65.00%	61.67%
Percentage Of Distributions classified as capital gain	0.00%	0.00%	0.00%
Percentage Of Distributions classified as non-taxable distribution	13.00%	35.00%	38.33%
Dividends, Preferred Stock	$ 6,900	$ 10,405	$ 7,992
Percentage Of Preferred Distributions classified as ordinary income	100.00%	100.00%	100.00%

Tax Credit Transactions (Details) $ in Thousands	12 Months Ended
Tax Credit Transactions (Details) $ in Thousands	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Aug. 27, 2010 USD ($)	Nov. 17, 2008 ft²
Tax Credit Transactions (Textuals) [Abstract]
Amount received in advance for project cost	$ 0	$ 0	$ 2,694
Historic tax credit transaction income	(11,853)	(11,840)	(12,026)
Deferred transaction costs	$ 122,954	122,243
Limit on tax credit claims under the Community Renewal Tax Relief	up to 39% of qualified investments in qualified, active low-income businesses or ventures
Historic Tax Credit Transaction [Member]
Tax Credit Transactions (Textuals) [Abstract]
Area of IRS Philadelphia Campus building (in square foot) \| ft²					862,692
Percentage of building leased to IRS					100.00%
Tax credit conditions	20% recapture per year beginning one year after the completion of the IRS Philadelphia Campus
Percentage of tax credit recapture	20.00%
Contribution allocated in non controlling interest	$ 2,800	2,600
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period	over the five year credit recapture period as defined in the Internal Revenue Code
Historic tax credit transaction income	$ 11,900
Allocated expenses within other income (expense)	500
Deferred transaction costs	$ 1,000	1,600
Rate of return on noncontrolling interest expected	2.00%
Accretion of non-controlling interest liability	$ 1,400	1,300	$ 1,300
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period in years	5 years
New Markets Tax Credit Transaction [Member]
Tax Credit Transactions (Textuals) [Abstract]
Tax credit conditions	100% recapture for a period of seven years as provided in the Internal Revenue Code
Percentage of tax credit recapture	100.00%
Percentage of qualified investments	39.00%
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period in years	7 years
Brandywine Realty Trust [Member] \| New Markets Tax Credit Transaction [Member]
Tax Credit Transactions (Textuals) [Abstract]
Deferred transaction costs	$ 5,300	5,300
USB [Member] \| Historic Tax Credit Transaction [Member]
Tax Credit Transactions (Textuals) [Abstract]
Agreed contribution in project cost by USB				$ 64,100
USB contributions presented within deferred income	26,800	39,100
Allocated expenses within other income (expense)	500
USB [Member] \| New Markets Tax Credit Transaction [Member]
Tax Credit Transactions (Textuals) [Abstract]
USB contributions presented within deferred income	$ 13,300	$ 13,300

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1,	$ (15,918)
Change during year	12,789	$ (7,338)	$ (4,499)
Settlement of interest rate swaps	0	(2,985)	0
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	286	297	153
Balance at December 31,	(2,995)	(15,918)
Accumulated Other Comprehensive Income (Loss) [Member]
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1,	(15,918)	(6,079)	(1,945)
Change during year	12,789	(7,338)	(4,499)
Non-controlling interest- consolidated real estate venture partner's share of unrealized (gains)/losses on derivative financial instruments	(152)	187	212
Settlement of interest rate swaps		(2,985)
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	286	297	153
Balance at December 31,	(2,995)	(15,918)	(6,079)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1,	(16,452)
Change during year	12,789	(7,338)	(4,499)
Settlement of interest rate swaps	0	(2,985)	0
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	286	297	153
Balance at December 31,	(3,377)	(16,452)
BRANDYWINE OPERATING PARTNERSHIP, L.P. \| Accumulated Other Comprehensive Income (Loss) [Member]
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1,	(16,452)	(6,426)	(2,080)
Change during year	12,789	(7,338)	(4,499)
Settlement of interest rate swaps		(2,985)
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	286	297	153
Balance at December 31,	$ (3,377)	$ (16,452)	$ (6,426)

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References + Details

Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
Segment Information (Details) $ in Thousands	Dec. 31, 2013 USD ($)	Sep. 30, 2013 USD ($)	Jun. 30, 2013 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2012 USD ($)	Jun. 30, 2012 USD ($)	Mar. 31, 2012 USD ($)	Dec. 31, 2013 USD ($) Reportable_Segments	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Oct. 16, 2013 Properties
Segment Reporting Information [Line Items]
Number of reportable segments \| Reportable_Segments									7
Real estate investments, at cost:
Operating properties	$ 4,669,289				$ 4,726,169				$ 4,669,289	$ 4,726,169	$ 4,793,080
Construction-in-progress	74,174				48,950				74,174	48,950	25,083
Land inventory	93,351				102,439				93,351	102,439	109,008
Total revenue	138,658	$ 143,354	$ 140,644	$ 139,554	136,395	$ 134,238	$ 131,530	$ 133,516	562,210	535,679	538,568
Property operating expenses, real estate taxes and third party management expenses									221,769	210,848	216,791
Net operating income									340,441	324,831	321,777
Equity Method Investments	180,512				193,555				180,512	193,555	115,807
Equity in income of real estate ventures									3,664	2,741	3,775
Pennsylvania Suburbs [Member]
Real estate investments, at cost:
Operating properties	1,199,105				1,178,730				1,199,105	1,178,730	1,218,071
Total revenue									153,426	150,075	148,887
Property operating expenses, real estate taxes and third party management expenses									54,506	52,657	54,734
Net operating income									98,920	97,418	94,153
Equity Method Investments	17,272				33,160				17,272	33,160	5,264
Equity in income of real estate ventures									925	520	1,861
Philadelphia CBD [Member]
Real estate investments, at cost:
Operating properties	1,300,666				988,590				1,300,666	988,590	953,870
Total revenue									146,081	131,592	125,366
Property operating expenses, real estate taxes and third party management expenses									55,702	50,787	48,831
Net operating income									90,379	80,805	76,535
Equity Method Investments	19,975				27,859				19,975	27,859	13,397
Equity in income of real estate ventures									1,547	1,113	466
Metropolitan, D.C. [Member]
Real estate investments, at cost:
Operating properties	1,214,965				1,193,200				1,214,965	1,193,200	1,255,803
Total revenue									116,048	107,656	119,255
Property operating expenses, real estate taxes and third party management expenses									42,641	41,485	45,135
Net operating income									73,407	66,171	74,120
Equity Method Investments	59,905				49,169				59,905	49,169	24,671
Equity in income of real estate ventures									130	(648)	(277)
New Jersey/ Delaware [Member]
Real estate investments, at cost:
Operating properties	414,716				546,644				414,716	546,644	545,657
Total revenue									60,262	59,671	58,960
Property operating expenses, real estate taxes and third party management expenses									29,981	28,506	30,564
Net operating income									30,281	31,165	28,396
Equity Method Investments	0				17,294				0	17,294	6,168
Equity in income of real estate ventures									1,245	1,803	1,157
Richmond, Virginia [Member]
Real estate investments, at cost:
Operating properties	310,397				309,923				310,397	309,923	307,698
Total revenue									35,058	35,701	36,789
Property operating expenses, real estate taxes and third party management expenses									14,916	14,484	14,739
Net operating income									20,142	21,217	22,050
Equity Method Investments	1,400				1,245				1,400	1,245	1,163
Equity in income of real estate ventures									381	269	510
Austin, Texas [Member]
Real estate investments, at cost:
Operating properties	36,856				285,346				36,856	285,346	257,694
Total revenue									31,451	32,379	30,894
Property operating expenses, real estate taxes and third party management expenses									13,298	13,951	13,034
Net operating income									18,153	18,428	17,860
Equity Method Investments	81,960				64,828				81,960	64,828	65,144
Equity in income of real estate ventures									(564)	(316)	58
California [Member]
Real estate investments, at cost:
Operating properties	192,584				223,736				192,584	223,736	254,287
Total revenue									18,369	17,463	16,692
Property operating expenses, real estate taxes and third party management expenses									9,411	9,043	9,407
Net operating income									8,958	8,420	7,285
Equity Method Investments	0				0				0	0	0
Equity in income of real estate ventures									0	0	0
Corporate [Member]
Real estate investments, at cost:
Operating properties	0				0				0	0	0
Construction-in-progress	74,174				48,950				74,174	48,950	25,083
Land inventory	93,351				102,439				93,351	102,439	109,008
Total revenue									1,515	1,142	1,725
Property operating expenses, real estate taxes and third party management expenses									1,314	(65)	347
Net operating income									201	1,207	1,378
Equity Method Investments	0				0				0	0	0
Equity in income of real estate ventures									0	0	0
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments, at cost:
Operating properties	4,669,289				4,726,169				4,669,289	4,726,169
Construction-in-progress	74,174				48,950				74,174	48,950
Land inventory	93,351				102,439				93,351	102,439
Total revenue									562,210	535,679	538,568
Equity Method Investments	$ 180,512				$ 193,555				180,512	193,555
Equity in income of real estate ventures									$ 3,664	$ 2,741	$ 3,775
Austin Joint Venture [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	50.00%								50.00%
Real estate investments, at cost:
Equity Method Investments	$ 17,262								$ 17,262
Equity in income of real estate ventures									$ (434)
Brandywine Realty Trust [Member] \| Austin Joint Venture [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage												50.00%
Real estate investments, at cost:
Number of properties contributed to a joint venture \| Properties												7

Segment Information (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
Segment Information (Details 1) - USD ($) $ in Thousands	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of consolidated net operating income
Consolidated net operating income									$ 340,441	$ 324,831	$ 321,777
Less:
Interest expense									(121,937)	(132,939)	(131,405)
Interest expense - amortization of deferred financing costs									(4,676)	(6,208)	(4,991)
Interest expense — financing obligation									(972)	(850)	0
Depreciation and amortization									(197,021)	(188,382)	(202,933)
Administrative expenses									(27,628)	(25,413)	(24,602)
Plus:
Interest income									1,044	3,008	1,810
Historic tax credit transaction income									11,853	11,840	12,026
Recognized hedge activity									0	(2,985)	0
Equity in income of real estate ventures									3,664	2,741	3,775
Net gain from remeasurement of investments in real estate ventures									6,866	0	0
Net gain on sale of interests in real estate									0	0	2,985
Net gain (loss) on sale of undepreciated real estate									(137)	0	0
Net gain (loss) on real estate venture transactions									29,604	(950)	(222)
Gain (loss) on early extinguishment of debt									(2,119)	(22,002)	(2,776)
Income (loss) from continuing operations									38,982	(37,309)	(24,556)
Income from discontinued operations									4,207	43,838	19,841
Net income (loss)	$ 21,002	$ 11,088	$ 7,180	$ 3,919	$ (26,698)	$ 17,089	$ 6,802	$ 9,336	$ 43,189	$ 6,529	$ (4,715)

Operating Leases (Details) $ in Thousands	Dec. 31, 2013 USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
Operating Leases, Future Minimum Payments Receivable, Current	$ 471,918
Operating Leases, Future Minimum Payments Receivable, in Two Years	457,315
Operating Leases, Future Minimum Payments Receivable, in Three Years	416,467
Operating Leases, Future Minimum Payments Receivable, in Four Years	358,368
Operating Leases, Future Minimum Payments Receivable, in Five Years	299,619
Operating Leases, Future Minimum Payments Receivable, Thereafter	$ 1,403,003

Commitments and Contingencies (Details) $ in Millions	9 Months Ended	12 Months Ended
Commitments and Contingencies (Details) $ in Millions	Sep. 30, 2004 USD ($)	Dec. 31, 2013 USD ($) ft² yr	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Commitments and Contingencies (Textuals) [Abstract]
Minimum remaining lease period \| yr		15
Maximum remaining lease period \| yr		75
Leased Area Of Building \| ft²		708,844
Amount to be paid if the Company takes fee title to Two Logan Square upon foreclosure of related mortgage		$ 2.9
Liability related to acquisition of TRC	$ 0.7	$ 1.6
Agreed holding period (not to sell) for properties acquired as part of the TRC acquisition		15 years
One Commerce Square [Member]
Commitments and Contingencies (Textuals) [Abstract]
Tax guarantee obligation		$ 130.0
Two Commerce Square [Member]
Commitments and Contingencies (Textuals) [Abstract]
Tax guarantee obligation		$ 107.9
One and Two Commerce Square [Member]
Commitments and Contingencies (Textuals) [Abstract]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		1.00%
Historic Tax Credit Transaction [Member]
Long-term Purchase Commitment [Line Items]
Accretion Of Non Controlling Interest Liability		$ 1.4	$ 1.3	$ 1.3
New Markets Tax Credit Transaction [Member]
Commitments and Contingencies (Textuals) [Abstract]
Tax Credit Carryforward, Amount		$ 7.8

Commitments and Contingencies (Ground Rent) (Details) - Ground Rent [Member] $ in Thousands	Dec. 31, 2013 USD ($)
Minimum future rental payments on non-cancelable leases
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 1,303
Operating Leases, Future Minimum Payments, Due in Two Years	1,303
Operating Leases, Future Minimum Payments, Due in Three Years	1,303
Operating Leases, Future Minimum Payments, Due in Four Years	1,303
Operating Leases, Future Minimum Payments, Due in Five Years	1,303
Operating Leases, Future Minimum Payments, Due Thereafter	57,540
Total	$ 64,055

Summary of Quarterly Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information [Line Items]
Real Estate Revenue, Net	$ 138,658	$ 143,354	$ 140,644	$ 139,554	$ 136,395	$ 134,238	$ 131,530	$ 133,516	$ 562,210	$ 535,679	$ 538,568
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	21,002	11,088	7,180	3,919	(26,698)	17,089	6,802	9,336	43,189	6,529	(4,715)
Net Income (Loss) Attributable to Parent	$ 18,975	$ 9,173	$ 5,308	$ 2,058	$ (30,832)	$ 13,949	$ 1,537	$ 7,108	$ 42,777	$ 6,595	$ (4,499)
Earnings Per Share, Basic	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ 0.23	$ (0.06)	$ (0.10)
Earnings Per Share, Diluted	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ 0.23	$ (0.06)	$ (0.10)
Restatement Adjustment [Member]
Quarterly Financial Information [Line Items]
Out of period stock compensation expense adjustment					$ 600
Overstatement (Understatement) of Expense due to Out of Period Adjustment					$ 600	$ (200)	$ (300)				$ (100)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References + Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Valuation and Qualifying Accounts Disclosure [Line Items]
Real Estate, Federal Income Tax Basis	$ 4,000,000
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance at Beginning of Period	16,646	$ 15,485	$ 15,222
Valuation Allowances and Reserves, Additions	1,384	1,891	928
Valuation Allowances and Reserves, Deductions	1,782	730	665
Valuation Allowances and Reserves, Balance at End of Period	$ 16,248	$ 16,646	$ 15,485

Schedule III - Real Estate and Accumulated Depreciation (Reconciliation of Real Estate and Accumulated Depreciation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at the Beginning of the Year	$ 4,726,169	$ 4,793,080	$ 4,834,111
Additions:
Acquisitions	347,510	50,579	31,454
Capital Expenditures	109,740	90,619	133,550
Less:
Dispositions	(474,275)	(168,408)	(163,971)
Balance at the End of the Year	4,669,289	4,726,169	4,793,080
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at the beginning of the year	954,665	865,710	776,078
Real Estate Accumulated Depreciation Additions [Abstract]
Depreciation expense — continuing operations	150,236	154,095	157,691
Depreciation expense — discontinued operations	9,164	2,143	1,185
SEC Schedule III, Real Estate, Other Deductions	(39,855)	(39,701)	(42,064)
Real Estate Accumulated Depreciation Less Dispositions [Abstract]
Dispositions	(91,890)	(28,270)	(62,022)
SEC Schedule III, Real Estate Accumulated Depreciation, Other Deductions	(38,367)	(39,013)	(7,222)
Balance at the end of the year	$ 983,808	$ 954,665	$ 865,710

Schedule III - Real Estate and Accumulated Depreciation (Aggregate Costs for Federal Income Tax Purposes and Ownership Percentage) (Details) $ in Billions	Dec. 31, 2013 USD ($)
Real Estate and Accumulated Depreciation [Line Items]
Real Estate, Federal Income Tax Basis	$ 4.0
3141 Fairview Park Drive [Member]
Real Estate and Accumulated Depreciation [Line Items]
Equity Method Investment, Ownership Percentage	50.00%