Consolidated Balance Sheets (Parenthetical) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Brandywine Realty Trust's equity:
Preferred shares, shares authorized	20,000,000	20,000,000
Common shares of Brandywine Realty Trust's beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares of Brandywine Realty Trust's beneficial interest, shares authorized	200,000,000	200,000,000
Common shares of Brandywine Realty Trust's beneficial interest, shares issued	143,022,150	142,690,755
Common shares of Brandywine Realty Trust's beneficial interest, shares outstanding	143,022,150	142,690,755
Common shares in grantor trust, shares	293,122	292,646
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Redeemable Limited Partnership, units issued	2,657,721	2,698,648
Redeemable Limited Partnership, units outstanding	2,657,721	2,698,648
General Partners' Capital account, units issued	143,022,150	142,690,755
General Partners' Capital account, units outstanding	143,022,150	142,690,755
7.50% Series C Preferred Shares
Brandywine Realty Trust's equity:
Preferred shares, dividend rate (as a percent)	7.50%	7.50%
Preferred shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares, shares issued	2,000,000	2,000,000
Preferred shares, shares outstanding	2,000,000	2,000,000
7.375% Series D Preferred Shares
Brandywine Realty Trust's equity:
Preferred shares, dividend rate (as a percent)	7.375%	7.375%
Preferred shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares, shares issued	2,300,000	2,300,000
Preferred shares, shares outstanding	2,300,000	2,300,000
7.50% Series D Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred shares, dividend rate (as a percent)	7.50%	7.50%
Preferred shares, shares issued	2,000,000	2,000,000
Preferred shares, shares outstanding	2,000,000	2,000,000
7.375% Series E Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred shares, dividend rate (as a percent)	7.375%	7.375%
Preferred shares, shares issued	2,300,000	2,300,000
Preferred shares, shares outstanding	2,300,000	2,300,000