Beneficiaries Equity of The Parent Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Numerator
Income (loss) from continuing operations, Basic	$ 7,080	$ 4,861	$ (3,414)	$ (9,278)
Income (loss) from continuing operations, Diluted	7,080	4,861	(3,414)	(9,278)
Net income (loss) from continuing operations attributable to non-controlling interests, Basic	(78)	(276)	244	88
Net income (loss) from continuing operations attributable to non-controlling interests, Diluted	(78)	(276)	244	88
Amount allocated to unvested restricted shareholders/unitholders, Basic	(95)	(121)	(286)	(384)
Amount allocable to unvested restricted shareholders, Diluted	(95)	(121)	(286)	(384)
Preferred share/unit dividends, Basic	(2,785)	(1,998)	(7,832)	(5,994)
Preferred share/unit dividends, Diluted	(2,785)	(1,998)	(7,832)	(5,994)
Redemption Premium, Basic	0	0	(2,090)	0
Redemption Premium, Diluted			(2,090)	0
Income (loss) from continuing operations available to common shareholders/unitholders, Basic	4,122	2,466	(13,378)	(15,568)
Income (loss) from continuing operations available to common shareholders/unitholders, Diluted	4,122	2,466	(13,378)	(15,568)
Income from discontinued operations	10,009	1,750	36,641	9,165
Income (loss) from discontinued operations, Diluted	10,009	1,750	36,641	9,165
Discontinued operations attributable to non-controlling interests - LP units	(182)	(86)	(669)	(234)
Discontinued operations attributable to non-controlling interests, diluted	(182)	(86)	(669)	(234)
Discontinued operations attributable to common shareholders, Basic	9,827	1,664	35,972	8,931
Discontinued operations attributable to common shareholders, Diluted	9,827	1,664	35,972	8,931
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	13,949	4,130	22,594	(6,637)
Net income (loss) available to common shareholders/unitholders, Diluted	$ 13,949	$ 4,130	$ 22,594	$ (6,637)
Denominator
Weighted-average units outstanding, Basic	143,424,485	135,562,487	143,182,911	135,164,424
Contingent securities/Stock based compensation	703,525	1,278,964
Weighted-average shares/units outstanding, Diluted	144,128,010	136,841,451	143,182,911	135,164,424
Earnings per Common Share:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic	$ 0.03	$ 0.02	$ (0.09)	$ (0.12)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted	$ 0.03	$ 0.02	$ (0.09)	$ (0.12)
Discontinued operations attributable to common shareholders/unitholders, Basic	$ 0.07	$ 0.01	$ 0.25	$ 0.07
Discontinued operations attributable to common shareholders, Diluted	$ 0.07	$ 0.01	$ 0.25	$ 0.07
Net income (loss) attributable to common shareholders/unitholders, Basic	$ 0.10	$ 0.03	$ 0.16	$ (0.05)
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ 0.10	$ 0.03	$ 0.16	$ (0.05)