PARTNERS' EQUITY OF THE PARENT COMPANY - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator
Net income	$ 53,992	$ 12,366	$ 307,326
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(456)	(421)	(410)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (456)	$ (421)	$ (410)
Denominator
Weighted average shares outstanding (in shares)	171,491,369	170,878,185	171,926,079
Contingent securities/Share based compensation (in shares)	834,277	1,395,055	390,997
Diluted weighted average shares outstanding (in shares)	172,325,646	172,273,240	172,317,076
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (in dollars per share)	$ 0.31	$ 0.07	$ 1.77
Net income attributable to common shareholders, Diluted (in dollars per share)	$ 0.31	$ 0.07	$ 1.77
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income	$ 53,992	$ 12,366	$ 307,326
Net income attributable to noncontrolling interests	2	3	(20)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(456)	(421)	(410)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(456)	(421)	(410)
Net income attributable to common unitholders, Basic	53,538	11,948	306,896
Net income attributable to common unitholders, Diluted	$ 53,538	$ 11,948	$ 306,896
Denominator
Weighted average shares outstanding (in shares)	172,036,481	171,770,843	172,907,713
Contingent securities/Share based compensation (in shares)	834,277	1,395,055	390,997
Diluted weighted average shares outstanding (in shares)	172,870,758	173,165,898	173,298,710
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (in dollars per share)	$ 0.31	$ 0.07	$ 1.77
Net income attributable to common shareholders, Diluted (in dollars per share)	$ 0.31	$ 0.07	$ 1.77