Partners' Equity Of The Parent Company - 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, 2021	Mar. 31, 2020
Numerator
Net income	$ 6,964	$ 8,087
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(146)	(131)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (146)	$ (131)
Denominator
Basic weighted average shares outstanding (in shares)	170,624,741	176,069,968
Contingent securities/Share based compensation (in shares)	1,011,379	583,491
Diluted weighted average shares outstanding (in shares)	171,636,120	176,653,459
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.04	$ 0.04
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.04	$ 0.04
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income	$ 6,964	$ 8,087
Net income attributable to noncontrolling interests	1	(12)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(146)	(131)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(146)	(131)
Net income attributable to common unitholders, Basic	6,819	7,944
Net income attributable to common unitholders, Diluted	$ 6,819	$ 7,944
Denominator
Basic weighted average shares outstanding (in shares)	171,606,375	177,051,602
Contingent securities/Share based compensation (in shares)	1,011,379	583,491
Diluted weighted average shares outstanding (in shares)	172,617,754	177,635,093
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.04	$ 0.04
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.04	$ 0.04