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
	Mar. 31, 2020	Mar. 31, 2019
Numerator
Net income	$ 8,087	$ 4,583
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(131)	(119)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (131)	$ (119)
Denominator
Basic weighted average shares outstanding (in shares)	176,069,968	175,857,358
Contingent securities/Share based compensation (in shares)	583,491	606,860
Diluted weighted average shares outstanding (in shares)	176,653,459	176,464,218
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.04	$ 0.03
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.04	$ 0.02
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income	$ 8,087	$ 4,583
Net income attributable to noncontrolling interests	(12)	(34)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(131)	(119)
Net income attributable to common unitholders, Basic	7,944	4,430
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(131)	(119)
Net income attributable to common unitholders, Diluted	$ 7,944	$ 4,430
Denominator
Basic weighted average shares outstanding (in shares)	177,051,602	176,840,229
Contingent securities/Share based compensation (in shares)	583,491	606,860
Diluted weighted average shares outstanding (in shares)	177,635,093	177,447,089
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.04	$ 0.03
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.04	$ 0.02