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				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator
Net income	$ 4,020	$ 8,087	$ 6,252	$ 4,583	$ 12,107	$ 10,835
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)		(93)		(224)	(212)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (93)		$ (93)		$ (224)	$ (212)
Denominator
Basic weighted average shares outstanding (in shares)	170,518,095		176,143,206		173,294,031	176,001,071
Contingent securities/Share based compensation (in shares)	251,983		547,618		311,917	577,069
Diluted weighted average shares outstanding (in shares)	170,770,078		176,690,824		173,605,948	176,578,140
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.02		$ 0.03		$ 0.07	$ 0.06
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.02		$ 0.03		$ 0.07	$ 0.06
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income	$ 4,020	$ 8,087	$ 6,252	$ 4,583	$ 12,107	$ 10,835
Net income attributable to noncontrolling interests	(10)		(13)		(22)	(47)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)		(93)		(224)	(212)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(93)		(93)		(224)	(212)
Net income attributable to common unitholders, Basic	3,917		6,146		11,861	10,576
Net income attributable to common unitholders, Diluted	$ 3,917		$ 6,146		$ 11,861	$ 10,576
Denominator
Basic weighted average shares outstanding (in shares)	171,499,729		177,125,064		174,275,665	176,983,433
Contingent securities/Share based compensation (in shares)	251,983		547,619		311,917	577,069
Diluted weighted average shares outstanding (in shares)	171,751,712		177,672,683		174,587,582	177,560,502
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.02		$ 0.03		$ 0.07	$ 0.06
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.02		$ 0.03		$ 0.07	$ 0.06