Partners Equity of The Operating Partnership (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)
Amount allocated to unvested restricted shareholders/unitholders, Basic	(95)	(121)	(286)	(384)
Amount allocable to unvested restricted unitholders, 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
Discontinued operations attributable to common unitholders	10,009	1,750	36,641	9,165
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
Incremental Common Shares Attributable to Share-based Payment Arrangements	703,525	1,278,964
Weighted-average shares/units outstanding, Diluted	144,128,010	136,841,451	143,182,911	135,164,424
Income per Common Partnership Unit:
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)
Income (Loss) From Discontinued Operations Diluted	10,009	1,750	36,641	9,165
BRANDYWINE OPERATING PARTNERSHIP, L.P.
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)
Amount allocated to unvested restricted shareholders/unitholders, Basic	(95)	(121)	(286)	(384)
Amount allocable to unvested restricted unitholders, 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 unitholders, Basic	4,200	2,742	(13,622)	(15,656)
Income (loss) from continuing operations available to common unit holders, Diluted	4,200	2,742	(13,622)	(15,656)
Discontinued operations attributable to common unitholders	10,009	1,750	36,641	9,165
Discontinued operations attributable to common unitholders, Diluted	10,009	1,750	36,641	9,165
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	14,209	4,492	23,019	(6,491)
Net income (loss) available to common shareholders/unitholders, Diluted	$ 14,209	$ 4,492	$ 23,019	$ (6,491)
Denominator
Weighted-average units outstanding, Basic	146,082,206	145,372,247	145,842,872	145,027,663
Incremental Common Shares Attributable to Share-based Payment Arrangements	703,525	1,278,964
Weighted-average shares/units outstanding, Diluted	146,785,731	146,651,211	145,842,872	145,027,663
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic	$ 0.03	$ 0.02	$ (0.09)	$ (0.11)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted	$ 0.03	$ 0.02	$ (0.09)	$ (0.11)
Discontinued operations attributable to common shareholders/unitholders, Basic	$ 0.07	$ 0.01	$ 0.25	$ 0.06
Discontinued operations attributable to common shareholders, Diluted	$ 0.07	$ 0.01	$ 0.25	$ 0.06
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)