Consolidated Statements of Partners' Equity - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	BRANDYWINE OPERATING PARTNERSHIP, L.P.	BRANDYWINE OPERATING PARTNERSHIP, L.P. General Partner Capital [Member]	BRANDYWINE OPERATING PARTNERSHIP, L.P. Accumulated Other Comprehensive Income (Loss) [Member]	BRANDYWINE OPERATING PARTNERSHIP, L.P. Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2017				$ 1,799,955	$ 1,795,684	$ 2,056	$ 2,215
Beginning Balance, Shares at Dec. 31, 2017					178,285,236
Net income	$ 44,445		$ 375	44,445	$ 44,440		5
Other comprehensive income (loss)	5,008	$ 4,966	42	5,008		5,008
Share Issuance from/(to) Deferred Compensation Plan	0			0
Share Issuance from/(to) Deferred Compensation Plan, Shares					66,830
Issuance of LP Units				416	$ 416
Issuance of LP Units, Shares					23,311
Issuance of partnership interest in consolidated real estate ventures	15		15	15			15
Distributions from consolidated real estate ventures	$ (54)		(54)	$ (54)			(54)
Share Choice Plan issuance	0			0	(1,285)
Share-based compensation activity	$ 3,076			$ 3,075	$ 3,075
Share-based compensation activity, Shares					68,425
Adjustment of redeemable partnership units to liquidation value at period end				3,604	$ 3,604
Distributions declared to general partnership unitholders				(32,259)	(32,259)
Ending Balance at Mar. 31, 2018				1,824,205	$ 1,814,960	7,064	2,181
Ending Balance, Shares at Mar. 31, 2018					178,442,517
Beginning Balance at Dec. 31, 2017				1,799,955	$ 1,795,684	2,056	2,215
Beginning Balance, Shares at Dec. 31, 2017					178,285,236
Net income	57,321			57,321
Other comprehensive income (loss)	6,879			6,879
Ending Balance at Jun. 30, 2018				1,805,756	$ 1,794,623	8,935	2,198
Ending Balance, Shares at Jun. 30, 2018					178,604,473
Beginning Balance at Mar. 31, 2018				1,824,205	$ 1,814,960	7,064	2,181
Beginning Balance, Shares at Mar. 31, 2018					178,442,517
Net income	12,876		129	12,876	$ 12,855		21
Other comprehensive income (loss)	1,871	1,856	15	1,871		1,871
Share Issuance from/(to) Deferred Compensation Plan	(111)			(111)	$ (111)
Share Issuance from/(to) Deferred Compensation Plan, Shares					34,230
Issuance of partnership interest in consolidated real estate ventures	(4)		(4)	(4)			(4)
Share-based compensation activity	1,139			1,140	$ 1,140
Share-based compensation activity, Shares					127,726
Adjustment of redeemable partnership units to liquidation value at period end				(1,991)	$ (1,991)
Distributions declared to general partnership unitholders				(32,230)	(32,230)
Ending Balance at Jun. 30, 2018				1,805,756	$ 1,794,623	8,935	2,198
Ending Balance, Shares at Jun. 30, 2018					178,604,473
Beginning Balance at Dec. 31, 2018				1,798,508	$ 1,791,591	4,725	2,192
Beginning Balance, Shares at Dec. 31, 2018					176,873,324
Cumulative effect of accounting change	(5,336)			(5,336)	$ (5,336)
Net income	4,583		60	4,583	$ 4,549		34
Other comprehensive income (loss)	(2,483)	(2,469)	(14)	(2,483)		(2,483)
Share Issuance from/(to) Deferred Compensation Plan	0			0
Share Issuance from/(to) Deferred Compensation Plan, Shares					(458)
Repurchase and retirement of LP units				(17,281)	$ (17,281)
Repurchase and retirement of LP units, Shares					(1,337,169)
Issuance of partnership interest in consolidated real estate ventures	22		22	22			22
Share-based compensation activity	3,677			3,677	$ 3,677
Share-based compensation activity, Shares					465,883
Adjustment of redeemable partnership units to liquidation value at period end				(3,088)	$ (3,088)
Distributions declared to general partnership unitholders				(33,560)	(33,560)
Ending Balance at Mar. 31, 2019				1,745,042	$ 1,740,552	2,242	2,248
Ending Balance, Shares at Mar. 31, 2019					176,001,580
Beginning Balance at Dec. 31, 2018				1,798,508	$ 1,791,591	4,725	2,192
Beginning Balance, Shares at Dec. 31, 2018					176,873,324
Net income	10,835			10,835
Other comprehensive income (loss)	(7,229)			(7,229)
Ending Balance at Jun. 30, 2019				1,715,445	$ 1,715,685	(2,504)	2,264
Ending Balance, Shares at Jun. 30, 2019					176,197,883
Beginning Balance at Mar. 31, 2019				1,745,042	$ 1,740,552	2,242	2,248
Beginning Balance, Shares at Mar. 31, 2019					176,001,580
Net income	6,252		47	6,252	$ 6,239		13
Other comprehensive income (loss)	(4,746)	$ (4,720)	(26)	(4,746)		(4,746)
Share Issuance from/(to) Deferred Compensation Plan	0			0
Share Issuance from/(to) Deferred Compensation Plan, Shares					100,908
Repurchase and retirement of LP units				0
Repurchase and retirement of LP units, Shares					1,245
Issuance of partnership interest in consolidated real estate ventures	3		$ 3	3			3
Share-based compensation activity	$ 1,451			1,451	$ 1,451
Share-based compensation activity, Shares					94,150
Adjustment of redeemable partnership units to liquidation value at period end				1,014	$ 1,014
Distributions declared to general partnership unitholders				(33,571)	(33,571)
Ending Balance at Jun. 30, 2019				$ 1,715,445	$ 1,715,685	$ (2,504)	$ 2,264
Ending Balance, Shares at Jun. 30, 2019					176,197,883