Partners Equity of The Operating Partnership (DetailsTextuals) (USD $)	9 Months Ended			9 Months Ended		12 Months Ended				0 Months Ended	9 Months Ended	0 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Series C Preferred Stock [Member]	Sep. 30, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2011 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Oct. 19, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Oct. 05, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Sep. 30, 2011 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Oct. 16, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P. 7.375% Series E Preferred Shares	Sep. 30, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P. 7.375% Series E Preferred Shares	Oct. 16, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P. 6.90% Series E-linked Preferred Units [Member]	Sep. 30, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P. 6.90% Series E-linked Preferred Units [Member]	Aug. 05, 2010 BRANDYWINE OPERATING PARTNERSHIP, L.P. Class F (2010) Units
Partners Equity of The Operating Partnership (Textuals) [Abstract]
Distribution Declared per common partnership unit							$ 0.15
Dividends Payable, Amount	$ 24,820,000	$ 23,505,000	$ 23,895,000		$ 24,820,000	$ 23,895,000		$ 21,600,000	$ 23,505,000
Percentage of Preferential return					6.90%	0.00%					7.375%		6.90%
Dividends, Preferred Stock, Cash	7,832,000	5,994,000		200,000						1,100,000		1,800,000
Partnership units issued for acquisition														7,111,112
Market price of shares on acquisition date														11.54
Dividend rate														$ 0.60