Beneficiaries Equity of the Parent Company Beneficiaries Equity of the Parent Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Numerator
Income (Loss) from Continuing Operations, Basic	$ (2,003)	$ (7,859)
Income (Loss) From Continuing Operations, Diluted	(2,003)	(7,859)
Net Loss (Income) From Continuing Operations Attributable to Non controlling interests, Basic	47	181
Net Loss (Income) From Continuing Operations Attributable To Non Controlling Interests, Diluted	47	181
Amount allocated to unvested restricted shareholders/unitholders, Basic	(108)	(96)
Amount allocated to unvested restricted shareholders/unitholders, Diluted	(108)	(96)
Preferred share/unit dividends, Basic	(1,725)	(1,998)
Preferred share/unit dividends, Diluted	(1,725)	(1,998)
Income (Loss) from Continuing Operations Available to Common Shareholders/unitholders, Basic	(3,789)	(9,772)
Income (Loss) from Continuing Operations Available to Common Shareholders/unitholders, Diluted	(3,789)	(9,772)
Income (Loss) from Discontinued Operations	5,922	17,195
Income (Loss) From Discontinued Operations, Diluted	5,922	17,195
Discontinued Operations Attributable to Noncontrolling Interests- Basic	(75)	(315)
Discontinued Operations Attributable to Noncontrolling Interests- Diluted	(75)	(315)
Discontinued operations attributable to common shareholders, Basic	5,847	16,880
Discontinued operations attributable to common shareholders, Diluted	5,847	16,880
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	2,058	7,108
Net Income (Loss) Available to Common Shareholders/unitholders, Diluted	$ 2,058	$ 7,108
Denominator
Weighted Average Number of Shares Outstanding, Basic	143,605,659	142,820,955
Weighted Average Number of Shares Outstanding, Diluted	143,605,659	142,820,955
Earnings per common share from continuing operations Abstract
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Basic Share	$ (0.03)	$ (0.07)
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Diluted Share	$ (0.03)	$ (0.07)
Discontinued Operations attributable to common shareholders/unitholders, Basic	$ 0.04	$ 0.12
Discontinued Operations attributable to common shareholders/unitholders, Diluted	$ 0.04	$ 0.12
Earnings Per Share, Basic	$ 0.01	$ 0.05
Earnings Per Share, Diluted	$ 0.01	$ 0.05