Partners Equity of the Operating Partnership (Details Textuals) (Details) (USD $)	0 Months Ended	3 Months Ended		12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended			0 Months Ended
	Apr. 10, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Mar. 31, 2014 6.90% Series E-linked Preferred Units [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Apr. 17, 2014 Dividend Paid [Member]	Apr. 17, 2014 Dividend Paid [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.	Apr. 15, 2014 Dividend Paid [Member] 6.90% Series E-linked Preferred Units [Member] BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share									$ 0.15
Stock Issued During Period, Shares, New Issues	12,650,000
Additional shares granted under option to purchase in public offering	1,650,000
Proceeds from Issuance of Common Stock	$ 181,500,000
Distributions payable		25,604,000		25,584,000	25,604,000	25,584,000		23,600,000	23,600,000
Preferred Stock, Dividend Rate, Percentage		6.90%		6.90%	6.90%	6.90%	6.90%
Preferred Stock, Liquidation Preference Per Share							$ 25.00
Dividends, Preferred Stock, Cash		$ 1,725,000	$ 1,725,000							$ 1,700,000