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. Series E-Linked Preferred Mirror Units	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
Partners' Equity, Beginning Balance at Dec. 31, 2016				$ 1,840,593	$ 96,850	$ (2,122)	$ 2,150	$ 1,743,715
Beginning Balance (in shares) at Dec. 31, 2016					4,000,000			175,140,760
Net income	$ 121,177		$ 1,004	121,177			29	$ 121,148
Other comprehensive income	4,178	$ 4,144	34	4,178		4,178
Redemption of Preferred Mirror Units				(96,850)	$ (96,850)
Redemption of Preferred Mirror Units (in shares)					(4,000,000)
Deferred compensation obligation	(768)			(768)				$ (768)
Deferred compensation obligation (in shares)								52,971
Issuance of LP Units				50,726				$ 50,726
Issuance of LP Units (in shares)								2,858,991
Issuance of partnership interest in consolidated real estate venture	85		85	85			85
Distributions from consolidated real estate venture	(48)		(48)	(48)			(48)
Share Choice Plan Issuance (in shares)								(1,423)
Bonus share issuance	110			110				$ 110
Bonus share issuance (in shares)								6,752
Share-based compensation activity	6,698			6,697				$ 6,697
Share-based compensation activity (in shares)								333,127
Adjustment of redeemable partnership units to liquidation value at period end				(4,096)			(1)	$ (4,095)
Preferred Share distributions	(2,032)			(2,032)				(2,032)
Preferred share redemption charge	(3,181)			(3,181)				(3,181)
Distributions declared to general partnership unitholders				(116,636)				(116,636)
Partners' Equity, Ending Balance at Dec. 31, 2017				1,799,955	$ 0	2,056	2,215	$ 1,795,684
Ending Balance (in shares) at Dec. 31, 2017					0			178,285,236
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	(111)			(111)				$ (111)
Deferred compensation obligation (in shares)								(99,189)
Issuance of LP Units				416				$ 416
Issuance of LP Units (in shares)								23,311
Repurchase and retirement of LP units				(21,858)				$ (21,858)
Repurchase and retirement of LP units (in shares)								(1,729,278)
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	5,845			5,848				$ 5,848
Share-based compensation activity (in shares)								196,151
Redemption value of limited partnership units				6,363				$ 6,363
Preferred Share distributions	0			0
Preferred share redemption charge	0			0
Distributions declared to general partnership unitholders				(130,168)				(130,168)
Partners' Equity, Ending Balance at Dec. 31, 2018	1,798,508			1,798,508	$ 0	4,725	2,192	$ 1,791,591
Ending Balance (in shares) at Dec. 31, 2018					0			176,873,324
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
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				(17,297)				$ (17,297)
Repurchase and retirement of LP units (in shares)								(1,337,169)
Issuance of partnership interest in consolidated real estate venture	27		27	27			27
Share-based compensation activity	10,027			10,027				$ 10,027
Share-based compensation activity (in shares)								845,210
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)
Preferred Share distributions	0			0
Preferred share redemption charge	$ 0			0
Distributions declared to general partnership unitholders				(134,324)				(134,324)
Partners' Equity, Ending Balance at Dec. 31, 2019				$ 1,672,915	$ 0	$ (2,715)	$ 1,091	$ 1,674,539
Ending Balance (in shares) at Dec. 31, 2019					0			176,480,095