BENEFICIARIES' EQUITY OF THE PARENT COMPANY - Number of Shares and Net Income Used to Calculate Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator
Net income	$ 6,101	$ 6,964
Net income attributable to noncontrolling interests	(8)	(43)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(148)	(146)
Net income attributable to noncontrolling interests, Diluted	(8)	(43)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(148)	(146)
Net income attributable to Common Partnership Unitholders of Brandywine Operating Partnership, L.P.	5,945	6,775
Net income attributable to common shareholders, diluted	$ 5,945	$ 6,775
Denominator
Weighted average units outstanding, basic (in shares)	171,294,949	170,624,741
Contingent securities/Share based compensation (in shares)	1,594,045	1,011,379
Weighted average units outstanding, diluted (in shares)	172,888,994	171,636,120
Earnings per Common Share:
Net income attributable to common shareholders, Basic (in dollars per share)	$ 0.03	$ 0.04
Net income attributable to common shareholders, Diluted (in dollars per share)	$ 0.03	$ 0.04