ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Parent Company
Beneficiaries' Equity, beginning balance		$ 1,701,219	$ 1,804,648	$ 1,688,303
Change in fair market value during year		5,371	4,817	(5,972)
Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests		(18)	(28)	29
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	564	752	752
Beneficiaries' Equity, ending balance		1,633,334	1,701,219	1,804,648
Operating Partnership
Change in fair market value during year		5,371	4,817	(5,972)
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	564	752	752
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Parent Company
Change in fair market value during year		5,371	4,817	(5,972)
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	564	752	752
Operating Partnership
Partners' Equity, beginning balance		1,690,079	1,793,082	1,672,915
Change in fair market value during year		5,371	4,817	(5,972)
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	564	752	752
Partners' Equity, ending balance		1,630,139	1,690,079	1,793,082
Accumulated Other Comprehensive Income (Loss)
Parent Company
Beneficiaries' Equity, beginning balance		(2,020)	(7,561)	(2,370)
Beneficiaries' Equity, ending balance		3,897	(2,020)	(7,561)
Accumulated Other Comprehensive Income (Loss) | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Operating Partnership
Partners' Equity, beginning balance		(2,366)	(7,935)	(2,715)
Partners' Equity, ending balance		$ 3,569	$ (2,366)	$ (7,935)

[1] Amounts reclassified from comprehensive income to interest expense within the Consolidated Statements of Operations.