Basis of Presentation - Statement of Partners' Equity (Details) - BRANDYWINE OPERATING PARTNERSHIP, L.P. - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total partners' equity	$ 1,715,445	$ 1,745,042	$ 1,798,508	$ 1,805,756	$ 1,824,205	$ 1,799,955
General Partner Capital [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total partners' equity	$ 1,715,685	1,740,552	1,791,591	1,794,623	1,814,960	1,795,684
As Previously Reported [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total partners' equity			1,820,053
As Previously Reported [Member] | General Partner Capital [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total partners' equity		1,761,580	1,813,136	1,814,870	1,834,947	1,815,411
Adjustments [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total partners' equity			(21,545)
Adjustments [Member] | General Partner Capital [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total partners' equity		$ (21,028)	$ (21,545)	$ (20,247)	$ (19,987)	$ (19,727)