Partners Equity of The Operating Partnership (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 09, 2014
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount	$ 28,871				$ 25,584				$ 28,871	$ 25,584
Dividends, Preferred Stock, Cash									6,900	6,900	10,405
Preferred shares, dividend rate (as a percent)									6.90%	6.90%
Numerator
Income (loss) from continuing operations, Basic									6,024	38,982	(37,309)
Income (loss) from continuing operations, Diluted									6,024	38,982	(37,309)
Amount allocated to unvested restricted shareholders									(349)	(363)	(376)
Amount allocated to unvested restricted shareholders, Diluted									(349)	(363)	(376)
Preferred share/unit dividends, Basic									(6,900)	(6,900)	(10,405)
Preferred share/unit dividends, Diluted									(6,900)	(6,900)	(10,405)
Net loss attributable to non-controlling interests									44	0	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted									(44)	0	0
Preferred share/unit redemption charge									0	0	(4,052)
Preferred share/unit redemption Premium, Diluted									0	0	(4,052)
Income Loss from continuing operations available to common shareholders/unitholders, Basic									(1,182)	31,362	(51,279)
Income Loss from continuing operations available to common shareholders Diluted									(1,182)	31,362	(51,279)
Discontinued operations attributable to common unitholders									918	4,207	43,838
Net income (loss) attributable to Common Shareholders/Unitholders									(274)	35,514	(8,238)
Net income (loss) available to common shareholders/unitholders, Diluted									(274)	35,514	(8,238)
Denominator
Weighted-average shares/units outstanding, Basic									166,202,649	153,140,458	143,257,097
Contingent securities/Stock based compensation									0	1,273,853	0
Weighted-average shares/units outstanding, Diluted									166,202,649	154,414,311	143,257,097
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ (0.01)	$ 0.20	$ (0.36)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									$ (0.01)	$ 0.20	$ (0.36)
Discontinued operations attributable to common shareholders/unitholders, Basic									$ 0.01	$ 0.03	$ 0.30
Discontinued operations attributable to common shareholders, Diluted									$ 0.01	$ 0.03	$ 0.30
Net income (loss) attributable to common shareholders/unitholders, Basic	$ (0.02)	$ 0.04	$ 0.00	$ (0.03)	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ 0.00	$ 0.23	$ (0.06)
Net income (loss) attributable to common shareholders/unitholders, Diluted	$ (0.02)	$ 0.04	$ 0.00	$ (0.03)	$ 0.12	$ 0.06	$ 0.03	$ 0.01	$ 0.00	$ 0.23	$ (0.06)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount	28,871				25,584				28,871	25,584
Preferred shares, dividend rate (as a percent)									6.90%	6.90%
Numerator
Income (loss) from continuing operations, Basic									6,024	38,982	(37,309)
Income (loss) from continuing operations, Diluted									6,024	38,982	(37,309)
Amount allocated to unvested restricted shareholders									(349)	(363)	(376)
Amount allocated to unvested restricted shareholders, Diluted									(349)	(363)	(376)
Preferred share/unit dividends, Basic									(6,900)	(6,900)	(10,405)
Preferred share/unit dividends, Diluted									(6,900)	(6,900)	(10,405)
Net loss attributable to non-controlling interests									44	0	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted									(44)	0	0
Preferred share/unit redemption charge									0	0	(4,052)
Preferred share/unit redemption Premium, Diluted									0	0	(4,052)
Income Loss from continuing operations available to common shareholders/unitholders, Basic									(1,181)	31,719	(52,142)
Income Loss from continuing operations available to common shareholders Diluted									(1,181)	31,719	(52,142)
Discontinued operations attributable to common unitholders									918	4,207	43,838
Discontinued operations attributable to common unitholders, Diluted									918	4,207	43,838
Net income (loss) attributable to Common Shareholders/Unitholders									(263)	35,926	(8,304)
Net income (loss) available to common shareholders/unitholders, Diluted									$ (263)	$ 35,926	$ (8,304)
Denominator
Weighted-average shares/units outstanding, Basic									167,942,246	154,929,545	145,883,217
Contingent securities/Stock based compensation									0	1,273,853	0
Weighted-average shares/units outstanding, Diluted									167,942,246	156,203,398	145,883,217
Income per Common Partnership Unit:
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Basic									$ (0.01)	$ 0.20	$ (0.36)
Income (Loss) from continuing operations attributable to common shareholders/unitholders, Diluted									$ (0.01)	$ 0.20	$ (0.36)
Discontinued operations attributable to common shareholders/unitholders, Basic									$ 0.01	$ 0.03	$ 0.30
Discontinued operations attributable to common shareholders, Diluted									$ 0.01	$ 0.03	$ 0.30
Net income (loss) attributable to common shareholders/unitholders, Basic									$ 0.00	$ 0.23	$ (0.06)
Net income (loss) attributable to common shareholders/unitholders, Diluted									$ 0.00	$ 0.23	$ (0.06)
Dividend Declared [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share												$ 0.15