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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Net income (loss)	$ 6,820	$ 6,252	$ 4,583	$ (43,522)	$ 12,876	$ 44,445	$ 17,655	$ 13,799
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)			(80)			(305)	(280)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (93)			$ (80)			$ (305)	$ (280)
Denominator
Basic weighted average shares outstanding (in shares)	176,195,244			178,602,622			176,066,507	178,515,993
Contingent securities/Share based compensation (in shares)	555,356			0			551,219	1,236,551
Diluted weighted average shares outstanding (in shares)	176,750,600			178,602,622			176,617,726	179,752,544
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.04			$ (0.24)			$ 0.10	$ 0.07
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.04			$ (0.24)			$ 0.10	$ 0.07
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income (loss)	$ 6,820	$ 6,252	$ 4,583	$ (43,522)	$ 12,876	$ 44,445	$ 17,655	$ 13,799
Net income attributable to noncontrolling interests	(11)			(20)			(58)	(46)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)			(80)			(305)	(280)
Net income attributable to common unitholders, Basic	6,716			(43,622)			17,292	13,473
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(93)			(80)			(305)	(280)
Net income attributable to common unitholders, Diluted	$ 6,716			$ (43,622)			$ 17,292	$ 13,473
Denominator
Basic weighted average shares outstanding (in shares)	177,176,870			180,082,421			177,048,621	179,995,792
Contingent securities/Share based compensation (in shares)	555,356			0			551,219	1,236,551
Diluted weighted average shares outstanding (in shares)	177,732,226			180,082,421			177,599,840	181,232,343
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.04			$ (0.24)			$ 0.10	$ 0.07
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.04			$ (0.24)			$ 0.10	$ 0.07