Partners Equity of the Operating Partnership Partners Equity of the Operating Partnership (Details Textuals) (Details) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended		12 Months Ended
	Oct. 15, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Oct. 19, 2015	Sep. 15, 2015
Earnings per Common Partnership Unit [Line Items]
Distributions Payable		$ 28,318		$ 28,871
Preferred Stock, Dividend Rate, Percentage		6.90%		6.90%
Dividends, Preferred Stock, Cash		$ 5,175	$ 5,175
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Distributions Payable		$ 28,318		$ 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					$ 26,600
Dividend Paid [Member] | Subsequent Event [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Distributions Payable					$ 26,600
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]
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share						$ 0.15
Dividend Declared [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share						$ 0.15