Consolidated Statements of Partners' Equity - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	BRANDYWINE OPERATING PARTNERSHIP, L.P.	BRANDYWINE OPERATING PARTNERSHIP, L.P. Cumulative Effect, Period of Adoption, Adjustment	BRANDYWINE OPERATING PARTNERSHIP, L.P. Accumulated Other Comprehensive Income (Loss)	BRANDYWINE OPERATING PARTNERSHIP, L.P. Noncontrolling Interests	BRANDYWINE OPERATING PARTNERSHIP, L.P. General Partner Capital	BRANDYWINE OPERATING PARTNERSHIP, L.P. General Partner Capital Cumulative Effect, Period of Adoption, Adjustment
Beginning balance (in shares) at Dec. 31, 2017								178,285,236
Partners' Equity, beginning balance at Dec. 31, 2017				$ 1,799,955		$ 2,056	$ 2,215	$ 1,795,684
Net income	$ 135,472		$ 954	135,472			55	$ 135,417
Other comprehensive income	2,669	$ 2,630	39	2,669		2,669
Deferred compensation obligation (in shares)								99,189
Deferred compensation obligation	(111)			(111)				$ (111)
Issuance of LP Units (in shares)								23,311
Issuance of LP Units				416				$ 416
Repurchase and retirement of LP units (in shares)								(1,729,278)
Repurchase and retirement of LP units				(21,858)				$ (21,858)
Issuance of partnership interest in consolidated real estate venture	16		16	16			16
Distributions from consolidated real estate venture	(94)		(94)	(94)			(94)
Share Choice Plan Issuance (in shares)								(1,285)
Share-based compensation activity (in shares)								196,151
Share-based compensation activity	5,845			5,848				$ 5,848
Redemption value of limited partnership units				6,363				6,363
Distributions declared to general partnership unitholders				(130,168)				$ (130,168)
Ending balance (in shares) at Dec. 31, 2018								176,873,324
Partners' Equity, ending balance at Dec. 31, 2018				1,798,508	$ (5,336)	4,725	2,192	$ 1,791,591	$ (5,336)
Net income	34,529		262	34,529			69	$ 34,460
Other comprehensive income	(7,440)	(7,399)	(41)	(7,440)		(7,440)
Deferred compensation obligation (in shares)								97,485
Deferred compensation obligation	0
Conversion of LP Units to common shares (in shares)								1,245
Conversion of LP Units to common shares				16				$ 16
Repurchase and retirement of LP units (in shares)								(1,337,169)
Repurchase and retirement of LP units				(17,297)				$ (17,297)
Issuance of partnership interest in consolidated real estate venture	27		27	27			27
Share-based compensation activity (in shares)								845,210
Share-based compensation activity	10,027			10,027				$ 10,027
Purchase of partnership interest in consolidated real estate venture	(2,180)		(1,197)				(1,197)	(983)
Adjustment of redeemable partnership units to liquidation value at period end				(3,615)				(3,615)
Distributions declared to general partnership unitholders				(134,324)				$ (134,324)
Ending balance (in shares) at Dec. 31, 2019								176,480,095
Partners' Equity, ending balance at Dec. 31, 2019				1,672,915		(2,715)	1,091	$ 1,674,539
Net income	307,326		1,799	307,326			20	$ 307,306
Other comprehensive income	(5,220)	$ (5,191)	$ (29)	(5,220)		(5,220)
Deferred compensation obligation (in shares)								32,256
Deferred compensation obligation	(206)			(206)				$ (206)
Repurchase and retirement of LP units (in shares)								(6,248,483)
Repurchase and retirement of LP units				(59,999)				$ (59,999)
Distributions from consolidated real estate venture	(22)			(22)			(22)
Share-based compensation activity (in shares)								309,096
Share-based compensation activity	6,236			6,236				$ 6,236
Sale of partnership interest to consolidated real estate venture	$ (1,017)
Adjustment of redeemable partnership units to liquidation value at period end				3,074				3,074
Distributions declared to general partnership unitholders				(130,005)				$ (130,005)
Ending balance (in shares) at Dec. 31, 2020								170,572,964
Partners' Equity, ending balance at Dec. 31, 2020				$ 1,793,082		$ (7,935)	$ 72	$ 1,800,945