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		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Income from continuing operations, Basic	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Net income from continuing operations attributable to non-controlling interests, Basic	(170)	(58)	(384)	(425)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(73)	(79)	(245)	(263)
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Net income attributable to Common Shareholders of Brandywine Realty Trust	18,803	6,022	42,173	47,008
Net income from continuing operations attributable to non-controlling interests, Diluted	(170)	(58)	(384)	(425)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(73)	(79)	(245)	(263)
Net income attributable to common shareholders, Diluted	$ 18,803	$ 6,022	$ 42,173	$ 47,008
Denominator
Basic weighted average shares outstanding (in shares)	175,433,657	175,127,110	175,315,581	174,976,998
Contingent securities/Share based compensation (in shares)	1,401,365	1,237,505	1,283,751	1,032,824
Diluted weighted average shares outstanding (in shares)	176,835,022	176,364,615	176,599,332	176,009,822
Earnings per Common Share:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27