CONSOLIDATED STATEMENTS OF PARTNERS’ EQUITY - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income	Noncontrolling Interest - Consolidated Real Estate Ventures	BRANDYWINE OPERATING PARTNERSHIP, L.P.	BRANDYWINE OPERATING PARTNERSHIP, L.P. Accumulated Other Comprehensive Income	BRANDYWINE OPERATING PARTNERSHIP, L.P. Noncontrolling Interest - Consolidated Real Estate Ventures	BRANDYWINE OPERATING PARTNERSHIP, L.P. General Partner Capital
Beginning balance (in shares) at Dec. 31, 2021							171,126,257
Beginning balance at Dec. 31, 2021				$ 1,690,079	$ (2,366)	$ 2,834	$ 1,689,611
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	$ 6,101		$ 8	6,101		(2)	$ 6,103
Other comprehensive (loss) income	3,952	$ 3,940	12	3,952	3,952
Deferred compensation obligation (in shares)							(19,406)
Deferred compensation obligation	(249)			(249)			$ (249)
Repurchase and retirement of LP units				(4,006)			$ (4,006)
Share-based compensation activity (in shares)							277,061
Share-based compensation activity	1,655			1,655			$ 1,655
Adjustment of redeemable partnership units to liquidation value at period end				3,704			3,704
Distributions declared to general partnership unit holders				(32,711)			$ (32,711)
Ending balance (in shares) at Mar. 31, 2022							171,383,912
Ending balance at Mar. 31, 2022				1,668,525	1,586	2,832	$ 1,664,107
Beginning balance (in shares) at Dec. 31, 2021							171,126,257
Beginning balance at Dec. 31, 2021				1,690,079	(2,366)	2,834	$ 1,689,611
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	24,230			24,230
Other comprehensive (loss) income	6,565			6,565
Ending balance (in shares) at Sep. 30, 2022							171,569,807
Ending balance at Sep. 30, 2022				1,631,416	4,199	2,829	$ 1,624,388
Beginning balance (in shares) at Mar. 31, 2022							171,383,912
Beginning balance at Mar. 31, 2022				1,668,525	1,586	2,832	$ 1,664,107
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	4,651		14	4,651		(2)	$ 4,653
Other comprehensive (loss) income	1,935	1,929	6	1,935	1,935
Deferred compensation obligation	0
Share-based compensation activity (in shares)							191,368
Share-based compensation activity	1,917			1,917			$ 1,917
Adjustment of redeemable partnership units to liquidation value at period end				2,181			2,181
Distributions declared to general partnership unit holders				(32,705)			$ (32,705)
Ending balance (in shares) at Jun. 30, 2022							171,575,280
Ending balance at Jun. 30, 2022				1,646,504	3,521	2,830	$ 1,640,153
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	13,478		37	13,478		(1)	$ 13,479
Other comprehensive (loss) income	678	676	2	678	678
Deferred compensation obligation (in shares)							(6,573)
Deferred compensation obligation	(63)			(63)			$ (63)
Share-based compensation activity (in shares)							1,100
Share-based compensation activity	2,094			2,094			$ 2,094
Adjustment of redeemable partnership units to liquidation value at period end				1,428			1,428
Distributions declared to general partnership unit holders				(32,703)			$ (32,703)
Ending balance (in shares) at Sep. 30, 2022							171,569,807
Ending balance at Sep. 30, 2022				1,631,416	4,199	2,829	$ 1,624,388
Beginning balance (in shares) at Dec. 31, 2022							171,569,807
Beginning balance at Dec. 31, 2022				1,630,139	3,569	2,832	$ 1,623,738
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	(5,276)		(17)	(5,276)		(1)	$ (5,275)
Other comprehensive (loss) income	(5,291)	(5,307)	16	(5,291)	(5,291)
Deferred compensation obligation (in shares)							(13,422)
Deferred compensation obligation	(88)			(88)			$ (88)
Share-based compensation activity (in shares)							171,318
Share-based compensation activity	3,371			3,371			$ 3,371
Adjustment of redeemable partnership units to liquidation value at period end				779			779
Distributions declared to general partnership unit holders				(32,734)			$ (32,734)
Ending balance (in shares) at Mar. 31, 2023							171,727,703
Ending balance at Mar. 31, 2023				1,590,900	(1,722)	2,831	$ 1,589,791
Beginning balance (in shares) at Dec. 31, 2022							171,569,807
Beginning balance at Dec. 31, 2022				1,630,139	3,569	2,832	$ 1,623,738
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	(39,649)			(39,649)
Other comprehensive (loss) income	4,240			4,240
Ending balance (in shares) at Sep. 30, 2023							172,097,661
Ending balance at Sep. 30, 2023				1,512,086	7,809	2,811	$ 1,501,466
Beginning balance (in shares) at Mar. 31, 2023							171,727,703
Beginning balance at Mar. 31, 2023				1,590,900	(1,722)	2,831	$ 1,589,791
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	(12,737)		(41)	(12,737)			$ (12,737)
Other comprehensive (loss) income	6,646	6,626	20	6,646	6,646
Deferred compensation obligation	0
Share-based compensation activity (in shares)							374,226
Share-based compensation activity	2,616			2,616			$ 2,616
Adjustment of redeemable partnership units to liquidation value at period end				(98)			(98)
Distributions declared to general partnership unit holders				(32,985)			$ (32,985)
Ending balance (in shares) at Jun. 30, 2023							172,101,929
Ending balance at Jun. 30, 2023				1,554,342	4,924	2,831	$ 1,546,587
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	(21,636)		(82)	(21,636)		(20)	$ (21,616)
Other comprehensive (loss) income	2,885	$ 2,909	$ (24)	2,885	2,885
Deferred compensation obligation (in shares)							(4,268)
Deferred compensation obligation	(20)			(20)			$ (20)
Share-based compensation activity	$ 2,506			2,506			2,506
Adjustment of redeemable partnership units to liquidation value at period end				(41)			(41)
Distributions declared to general partnership unit holders				(25,950)			$ (25,950)
Ending balance (in shares) at Sep. 30, 2023							172,097,661
Ending balance at Sep. 30, 2023				$ 1,512,086	$ 7,809	$ 2,811	$ 1,501,466