Partners Equity of the Operating Partnership - Number of Units and Net Income Used to Calculate Basic and Diluted Earnings Per Common Partnership Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Income from continuing operations, Basic	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(73)	(79)	(245)	(263)
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (73)	$ (79)	$ (245)	$ (263)
Denominator
Basic weighted average shares outstanding (in shares)	175,433,657	175,127,110	175,315,581	174,976,998
Contingent securities/Share based compensation (in shares)	1,401,365	1,237,505	1,283,751	1,032,824
Diluted weighted average shares outstanding (in shares)	176,835,022	176,364,615	176,599,332	176,009,822
Earnings per Common Partnership Unit
Net income attributable to common unitholders, Basic (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Net income attributable to common unitholders, Diluted (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Income from continuing operations, Basic	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(73)	(79)	(245)	(263)
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Net income attributable to non-controlling interests	(12)	(6)	(26)	(12)
Net income attributable to common unitholders, Basic	18,961	6,074	42,531	47,421
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(73)	(79)	(245)	(263)
Net income attributable to common unitholders, Diluted	$ 18,961	$ 6,074	$ 42,531	$ 47,421
Denominator
Basic weighted average shares outstanding (in shares)	176,913,456	176,606,909	176,795,380	176,491,311
Contingent securities/Share based compensation (in shares)	1,401,365	1,237,505	1,283,751	1,032,824
Diluted weighted average shares outstanding (in shares)	178,314,821	177,844,414	178,079,131	177,524,135
Earnings per Common Partnership Unit
Net income attributable to common unitholders, Basic (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Net income attributable to common unitholders, Diluted (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27