BENEFICIARIES' EQUITY OF THE PARENT COMPANY - Schedule of 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, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator
Net income (loss)	$ (12,737)	$ (5,276)	$ 4,651	$ 6,101	$ (18,013)	$ 10,752
Net (income) loss attributable to noncontrolling interests, Basic	41		(14)		58	(22)
Net (income) loss attributable to noncontrolling interests, Diluted	41		(14)		58	(22)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(204)		(98)		(274)	(246)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(204)		(98)		(274)	(246)
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	(12,900)		4,539		(18,229)	10,484
Net income (loss) attributable to common shareholders, diluted	$ (12,900)		$ 4,539		$ (18,229)	$ 10,484
Denominator
Basic weighted average shares outstanding (in shares)	171,962,162		171,527,031		171,818,463	171,411,631
Contingent securities/Share based compensation (in shares)	0		733,398		0	1,163,777
Weighted average shares outstanding, diluted (in shares)	171,962,162		172,260,429		171,818,463	172,575,408
Earnings (loss) per Common Share:
Net income (loss) attributable to common shareholders, Basic (in dollars per share)	$ (0.08)		$ 0.03		$ (0.11)	$ 0.06
Net income (loss) attributable to common shareholders, Diluted (in dollars per share)	$ (0.08)		$ 0.03		$ (0.11)	$ 0.06