Beneficiaries Equity of the Parent Company (Details Textuals) (Details) (USD $)	0 Months Ended	3 Months Ended		12 Months Ended	3 Months Ended					0 Months Ended	3 Months Ended	12 Months Ended
	Apr. 10, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Class A Units [Member]	Mar. 31, 2014 Series E Preferred Stock [Member]	Nov. 05, 2013 Offering Program [Member]	Apr. 17, 2014 Dividend Declared [Member]	Apr. 17, 2014 Dividend Paid [Member]	Apr. 15, 2014 Dividend Paid [Member] Series E Preferred Stock [Member]	Mar. 31, 2014 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Apr. 17, 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
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
Dividends Payable, Amount Per Share								$ 0.15					$ 0.15
Distributions payable		25,604,000		25,584,000					23,600,000		25,604,000	25,584,000	23,600,000
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		$ 1,725,000	$ 1,725,000							$ 1,700,000
Shares Authorized For Equity Offering Program							16,000,000
Remaining Shares Available For Sales							16,000,000
Common Stock, Shares Authorized		200,000,000		200,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased		539,200