Beneficiaries Equity of the Parent Company (Details Textuals) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		12 Months Ended				6 Months Ended					0 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	May 15, 2014	May 14, 2014	Feb. 07, 2014	Jun. 30, 2014 Class A Units [Member]	Jun. 30, 2013 Class A Units [Member]	Jun. 30, 2014 Series E Preferred Stock [Member]	Nov. 05, 2013 Offering Program [Member]	Jul. 07, 2014 Dividend Paid [Member]	Jul. 15, 2014 Dividend Paid [Member] Series E Preferred Stock [Member]	Jun. 30, 2014 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Jun. 30, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Jul. 07, 2014 BRANDYWINE OPERATING PARTNERSHIP, L.P. Dividend Paid [Member]
Class of Stock [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount							1,763,739	1,763,739
Proceeds from Issuance of Common Stock	$ 0	$ 181,527											$ 0	$ 181,527
Dividends Payable, Amount Per Share						$ 0.15
Distributions payable	25,588		25,584								23,600		25,588		25,584	23,900
Preferred Stock, Shares Issued	4,000,000		4,000,000										4,000,000		4,000,000
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	$ 3,450	$ 3,450										$ 1,700
Shares of Beneficial Interest, Shares Authorized				420,000,000	220,000,000
Shares Authorized For Equity Offering Program										16,000,000
Remaining Shares Available For Sales										16,000,000
Common Stock, Shares Authorized	400,000,000		200,000,000	400,000,000	200,000,000
Preferred Stock, Shares Authorized	20,000,000		20,000,000	20,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	539,200