Partners Equity of the Operating Partnership Partners Equity of the Operating Partnership (Details Textuals) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended	0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Apr. 15, 2015	Apr. 06, 2015	Mar. 11, 2015
Earnings per Common Partnership Unit [Line Items]
Distributions payable	$ 29,038		$ 28,871
Preferred Stock, Dividend Rate, Percentage	6.90%		6.90%
Dividends, Preferred Stock, Cash	1,725	1,725
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Distributions payable	29,038		28,871
Preferred Stock, Dividend Rate, Percentage	6.90%		6.90%
6.90% Series E-linked Preferred Units [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Preferred Stock, Dividend Rate, Percentage	6.90%
Preferred Stock, Liquidation Preference Per Share	$ 25.00
Dividend Paid [Member] | Subsequent Event [Member]
Earnings per Common Partnership Unit [Line Items]
Distributions payable					27,300
Dividend Paid [Member] | Subsequent Event [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Distributions payable					27,300
Dividend Paid [Member] | Subsequent Event [Member] | 6.90% Series E-linked Preferred Units [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Dividends, Preferred Stock, Cash				$ 1,700
Dividend Declared [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share						$ 0.15