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