Partners Equity of the Operating Partnership (Details Textuals) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			3 Months Ended	12 Months Ended		0 Months Ended	3 Months Ended	36 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Mar. 13, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Apr. 15, 2013 6.90% Series E-linked Preferred Units [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Mar. 31, 2013 6.90% Series E-linked Preferred Units [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Mar. 10, 2013 Offering Program [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Distribution Declared Per Common Partnership Unit						$ 0.15
Distributions payable	$ 23,684		$ 23,652	$ 23,684	$ 23,652	$ 21,700
Preferred Stock, Dividend Rate, Percentage				6.90%	6.90%			6.90%
Preferred Stock, Liquidation Preference Per Share								$ 25.00
Dividends, Preferred Stock, Cash	$ (1,725)	$ (1,998)					$ 1,700
Number Of Shares Sold By Company									6,421,553
Average Sales Price Per Share									$ 12.50