Partners Equity of The Operating Partnership (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Numerator
Income (loss) from continuing operations, Basic									$ (30,154)	$ (18,965)	$ (37,325)
Income (loss) from continuing operations, Diluted									(30,154)	(18,965)	(37,325)
Amount allocated to unvested restricted shareholders/unitholders, Basic									(376)	(505)	(512)
Amount allocable to unvested restricted unitholders, Diluted									(376)	(505)	(512)
Preferred share/unit dividends, Basic									(10,405)	(7,992)	(7,992)
Preferred share/unit dividends, Diluted									(10,405)	(7,992)	(7,992)
Redemption Premium, Basic									(4,052)	0	0
Redemption Premium, Diluted									(4,052)	0	0
Discontinued operations attributable to common unitholders									36,683	14,250	19,719
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust									(8,238)	(12,996)	(25,578)
Net income (loss) available to common shareholders/unitholders, Diluted									(8,238)	(12,996)	(25,578)
Denominator
Weighted-average units outstanding, Basic									143,257,097	135,444,424	131,743,275
Weighted-average shares/units outstanding, Diluted									143,257,097	135,444,424	131,743,275
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ (0.31)	$ (0.20)	$ (0.34)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									$ (0.31)	$ (0.20)	$ (0.34)
Discontinued operations attributable to common shareholders/unitholders, Basic									$ 0.25	$ 0.10	$ 0.15
Discontinued operations attributable to common shareholders, Diluted									$ 0.25	$ 0.10	$ 0.15
Net income (loss) attributable to common shareholders/unitholders, Basic	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ (0.05)	$ 0.03	$ (0.06)	$ (0.02)	$ (0.06)	$ (0.10)	$ (0.19)
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ (0.21)	$ 0.10	$ 0.01	$ 0.05	$ (0.05)	$ 0.03	$ (0.06)	$ (0.02)	$ (0.06)	$ (0.10)	$ (0.19)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Income (loss) from continuing operations, Basic									(30,154)	(18,965)	(37,325)
Income (loss) from continuing operations, Diluted									(30,154)	(18,965)	(37,325)
Amount allocated to unvested restricted shareholders/unitholders, Basic									(376)	(505)	(512)
Amount allocable to unvested restricted unitholders, Diluted									(376)	(505)	(512)
Preferred share/unit dividends, Basic									(10,405)	(7,992)	(7,992)
Preferred share/unit dividends, Diluted									(10,405)	(7,992)	(7,992)
Redemption Premium, Basic									(4,052)	0	0
Redemption Premium, Diluted									(4,052)	0	0
Income (loss) from continuing operations available to common unitholders, Basic									(44,987)	(27,462)	(45,829)
Income (loss) from continuing operations available to common unit holders, Diluted									(44,987)	(27,462)	(45,829)
Discontinued operations attributable to common unitholders									36,683	14,250	19,719
Discontinued operations attributable to common unitholders, Diluted									36,683	14,250	19,719
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust									(8,304)	(13,212)	(26,110)
Net income (loss) available to common shareholders/unitholders, Diluted									$ (8,304)	$ (13,212)	$ (26,110)
Denominator
Weighted-average units outstanding, Basic									145,883,217	145,118,841	137,454,796
Weighted-average shares/units outstanding, Diluted									145,883,217	145,118,841	137,454,796
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ (0.31)	$ (0.19)	$ (0.33)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									$ (0.31)	$ (0.19)	$ (0.33)
Discontinued operations attributable to common shareholders/unitholders, Basic									$ 0.25	$ 0.10	$ 0.14
Discontinued operations attributable to common shareholders, Diluted									$ 0.25	$ 0.10	$ 0.14
Net income (loss) attributable to common shareholders/unitholders, Basic									$ (0.06)	$ (0.09)	$ (0.19)
Net income (loss) attributable to common shareholders/unitholders, Diluted									$ (0.06)	$ (0.09)	$ (0.19)