PARTNERS' EQUITY OF THE PARENT COMPANY - Schedule of 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						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Numerator
Net loss	$ (25,998)	$ (88,936)	$ (27,056)	$ (165,720)	$ 30,267	$ (16,414)	$ (141,990)	$ (151,867)
Basic
Nonforfeitable dividends allocated to unvested restricted shareholders	(313)			(276)			(1,064)	(889)
Diluted
Nonforfeitable dividends allocated to unvested restricted unitholders, diluted	$ (313)			$ (276)			$ (1,064)	$ (889)
Denominator
Weighted average shares outstanding, basic (in shares)	173,699,312			172,668,731			173,385,330	172,480,325
Weighted average shares outstanding, diluted (in shares)	173,699,312			172,668,731			173,385,330	172,480,325
Loss per Common Partnership Unit:
Net loss attributable to common shareholders, basic (in dollars per share)	$ (0.15)			$ (0.96)			$ (0.82)	$ (0.88)
Net loss attributable to common shareholders, diluted (in dollars per share)	$ (0.15)			$ (0.96)			$ (0.82)	$ (0.88)
Brandywine Operating Partnership, L.P.
Numerator
Net loss	$ (25,998)	$ (88,936)	$ (27,056)	$ (165,720)	$ 30,267	$ (16,414)	$ (141,990)	$ (151,867)
Basic
Net (income) loss attributable to noncontrolling interests	1			3			1	(3)
Nonforfeitable dividends allocated to unvested restricted shareholders	(313)			(276)			(1,064)	(889)
Net loss attributable to common unitholders	(26,310)			(165,993)			(143,053)	(152,759)
Diluted
Nonforfeitable dividends allocated to unvested restricted unitholders, diluted	(313)			(276)			(1,064)	(889)
Net loss attributable to common unitholders	$ (26,310)			$ (165,993)			$ (143,053)	$ (152,759)
Denominator
Weighted average shares outstanding, basic (in shares)	174,214,907			173,184,325			173,900,925	172,995,920
Weighted average shares outstanding, diluted (in shares)	174,214,907			173,184,325			173,900,925	172,995,920
Loss per Common Partnership Unit:
Net loss attributable to common shareholders, basic (in dollars per share)	$ (0.15)			$ (0.96)			$ (0.82)	$ (0.88)
Net loss attributable to common shareholders, diluted (in dollars per share)	$ (0.15)			$ (0.96)			$ (0.82)	$ (0.88)