Beneficiaries Equity of The Parent Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Numerator
Loss from continuing operations, Basic	$ (5,889)	$ (1,567)
Loss from continuing operations, Diluted	(5,889)	(1,567)
Net income from continuing operations attributable to non-controlling interests, Basic	145	73
Net income from continuing operations attributable to non-controlling interests, Diluted	145	73
Amount allocated to unvested restricted shareholders/unitholders, Basic	(96)	(142)
Amount allocable to unvested restricted shareholders, Diluted	(96)	(142)
Preferred share dividends, Basic	(1,998)	(1,998)
Preferred share dividends, Diluted	(1,998)	(1,998)
Loss from continuing operations available to common shareholders, Basic	(7,838)	(3,634)
Loss from continuing operations available to common shareholders, Diluted	(7,838)	(3,634)
Income (loss) from discontinued operations	15,225	1,077
Income (loss) from discontinued operations, Diluted	15,225	1,077
Discontinued operations attributable to non-controlling interests - LP units	(279)	(22)
Discontinued operations attributable to non-controlling interests, diluted	(279)	(22)
Discontinued operations attributable to common shareholders, Basic	14,946	1,055
Discontinued operations attributable to common shareholders, Diluted	14,946	1,055
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	7,108	(2,579)
Net income (loss) available to common shareholders, Diluted	$ 7,108	$ (2,579)
Denominator
Weighted-average units outstanding, Basic	142,820,955	134,577,421
Contingent securities/Stock based compensation	0	0
Weighted-average shares/units outstanding, Diluted	142,820,955	134,577,421
Earnings per Common Share:
Loss from continuing operations attributable to common shareholders/unitholders, Basic	$ (0.05)	$ (0.03)
Loss from continuing operations attributable to common shareholders/unitholders, Diluted	$ (0.05)	$ (0.03)
Discontinued operations attributable to common shareholders, Basic	$ 0.10	$ 0.01
Discontinued operations attributable to common shareholders, Diluted	$ 0.10	$ 0.01
Net income (loss) attributable to common shareholders/unitholders, Basic	$ 0.05	$ (0.02)
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ 0.05	$ (0.02)