Beneficiaries Equity of the Parent Company - Number of Shares and Net Income Used to Calculate Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator
Net income	$ 4,020	$ 8,087	$ 6,252	$ 4,583	$ 12,107	$ 10,835
Net income attributable to noncontrolling interests, Basic	(24)		(47)		(89)	(107)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)		(93)		(224)	(212)
Net income attributable to noncontrolling interests, Diluted	(24)		(47)		(89)	(107)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(93)		(93)		(224)	(212)
Net income attributable to Common Shareholders of Brandywine Realty Trust	3,903		6,112		11,794	10,516
Net income attributable to common shareholders, Diluted	$ 3,903		$ 6,112		$ 11,794	$ 10,516
Denominator
Basic weighted average shares outstanding (in shares)	170,518,095		176,143,206		173,294,031	176,001,071
Contingent securities/Share based compensation (in shares)	251,983		547,618		311,917	577,069
Diluted weighted average shares outstanding (in shares)	170,770,078		176,690,824		173,605,948	176,578,140
Earnings per Common Share:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.02		$ 0.03		$ 0.07	$ 0.06
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.02		$ 0.03		$ 0.07	$ 0.06