Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2011	Dec. 31, 2010
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	$ 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	135,579,643	134,601,796
Common shares of Brandywine Realty Trust's beneficial interest, shares outstanding	135,579,643	134,485,117
Common shares in treasury, at cost, shares	0	116,679
Common shares in grantor trust, shares	292,646	291,281
BRANDYWINE OPERATING PARTNERSHIP, L.P. | 7.50% Series D Preferred Shares
Brandywine Realty Trust's equity:
Preferred shares, shares issued	2,000,000	2,000,000
Preferred shares, shares outstanding	2,000,000	2,000,000
7.50% Series C Preferred Shares
Brandywine Realty Trust's equity:
Preferred shares, par value	$ 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, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	2,300,000	2,300,000
Preferred shares, shares outstanding	2,300,000	2,300,000
BRANDYWINE OPERATING PARTNERSHIP, L.P. | 7.375% Series E Preferred Shares
Brandywine Realty Trust's equity:
Preferred shares, shares issued	2,300,000	2,300,000
Preferred shares, shares outstanding	2,300,000	2,300,000
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
General Partners' Capital account, units issued	135,579,643	134,601,796
General Partners' Capital account, units outstanding	135,579,643	134,485,117
Redeemable limited partnership, units issued	9,809,759	9,902,752
Redeemable limited partnership, units outstanding	9,809,759	9,902,752