Beneficiaries Equity of The Parent Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Numerator
Income (loss) from continuing operations, Basic													$ (13,232)	$ (31,276)	$ 3,588
Income (loss) from continuing operations, Diluted													(13,232)	(31,276)	3,588
Net (loss) income from continuing operations attributable to non-controlling interests, Basic													548	820	58
Net (loss) income from continuing operations attributable to non-controlling interests, Diluted													548	820	58
Amount allocated to unvested restricted shareholders/unitholders, Basic													(505)	(512)	(279)
Amount allocable to unvested restricted shareholders, Diluted													(505)	(512)	(279)
Preferred share dividends, Basic													(7,992)	(7,992)	(7,992)
Preferred share dividends, Diluted													(7,992)	(7,992)	(7,992)
Loss from continuing operations available to common shareholders, Basic													(21,181)	(38,960)	(4,625)
Loss from continuing operations available to common shareholders, Diluted													(21,181)	(38,960)	(4,625)
Income from discontinued operations													8,517	13,670	4,501
Income from discontinued operations, Diluted													8,517	13,670	4,501
Discontinued operations attributable to non-controlling interests - LP units													(332)	(288)	(91)
Net income (loss) attributable to noncontrolling interest, joint venture partners and income (loss) from discontinued operations, net of tax, attributable to noncontrolling interest															(121)
Discontinued operations attributable to non-controlling interests, diluted													(332)	(288)	(121)
Discontinued operations attributable to common shareholders, Basic													8,185	13,382	4,380
Discontinued operations attributable to common shareholders, Diluted													8,185	13,382	4,380
Net loss attributable to Common Shareholders of Brandywine Realty Trust													(12,996)	(25,578)	(245)
Net loss available to common shareholders, Diluted													$ (12,996)	$ (25,578)	$ (245)
Denominator
Basic weighted average shares outstanding													135,444,424	131,743,275	111,898,045
Contingent securities/Stock based compensation															1,353,246
Weighted-average shares/units outstanding, Diluted													135,444,424	131,743,275	113,251,291
Earnings (loss) per Common Share:
Loss from continuing operations attributable to common shareholders/unitholders, Basic													$ (0.16)	$ (0.29)	$ (0.04)
Loss from continuing operations attributable to common shareholders/unitholders, Diluted													$ (0.16)	$ (0.29)	$ (0.04)
Discontinued operations attributable to common shareholders, Basic													$ 0.06	$ 0.10	$ 0.04
Discontinued operations attributable to common shareholders, Diluted													$ 0.06	$ 0.10	$ 0.04
Net loss attributable to common shareholders/unitholders, Basic	$ (0.05)	$ 0.03	$ (0.06)	[1]	$ (0.02)	[2]	$ (0.05)	$ (0.06)	$ (0.06)	[1]	$ (0.02)	[2]	$ (0.10)	$ (0.19)	$ 0.00
Net loss attributable to common shareholders/unitholders, Diluted	$ (0.05)	$ 0.03	$ (0.06)	[1]	$ (0.02)	[2]	$ (0.05)	$ (0.06)	$ (0.06)	[1]	$ (0.02)	[2]	$ (0.10)	$ (0.19)	$ 0.00

[1] The consolidated statement of operations for the second quarter of 2011 also 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 million in the current year. 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 in the current year is not material to the Company's consolidated financial statements, the Company recorded the related adjustment during the current year.

[2] During the first quarter of 2011, the Company recorded additional income of $0.5 million related to electricity charges in prior years that were under-billed to a certain tenant. This resulted in the overstatement of total revenue by $0.5 million during the current year and in the understatement of total revenue by $0.3 million and $0.2 million for the years ended December 31, 2009 and 2008, respectively. 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.