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
	Mar. 31, 2019	Mar. 31, 2018
Numerator
Net income	$ 4,066	$ 44,705
Net income attributable to noncontrolling interests, Basic	(57)	(376)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(119)	(114)
Net income attributable to Common Shareholders of Brandywine Realty Trust	3,890	44,215
Net income attributable to noncontrolling interests, Diluted	(57)	(376)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(119)	(114)
Net income attributable to common shareholders, Diluted	$ 3,890	$ 44,215
Denominator
Basic weighted average shares outstanding (in shares)	175,857,358	178,395,525
Basic contingent securities/Share based compensation (in shares)	0	0
Contingent securities/Share based compensation (in shares)	606,860	1,392,786
Diluted weighted average shares outstanding (in shares)	176,464,218	179,788,311
Earnings per Common Share:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.02	$ 0.25
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.02	$ 0.25