Beneficiaries Equity of the Parent Company Beneficiaries Equity of the Parent Company (Details Textuals) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	6 Months Ended			6 Months Ended	12 Months Ended	0 Months Ended	6 Months Ended			6 Months Ended		12 Months Ended		36 Months Ended
	Apr. 10, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Class A Units [Member]	Dec. 31, 2012 Class A Units [Member]	Jul. 15, 2013 Series E Preferred Stock [Member]	Jun. 30, 2013 Series E Preferred Stock [Member]	May 30, 2013 Dividend Declared [Member]	May 30, 2013 Dividend Paid [Member]	Jun. 30, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Jun. 30, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.	May 30, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Mar. 10, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P. Offering Program [Member]
Class of Stock [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount					1,763,739	2,657,721
Common stock issued subsequent to balance sheet date, New issues	12,650,000
Additional shares granted under option to purchase in public offering	1,650,000
Proceeds from Issuance of Common Stock	$ 181,700	$ 181,527	$ 0								$ 181,527	$ 0
Distribution Declared Per Common Partnership Unit									$ 0.15					$ 0.15
Distributions payable		25,587		23,652						23,800	25,587		23,652	23,800
Preferred Stock, Shares Issued											4,000,000		4,000,000
Preferred Stock, Dividend Rate, Percentage								6.90%			6.90%		6.90%
Preferred Stock, Liquidation Preference Per Share								$ 25.00
Dividends, Preferred Stock, Cash		$ 3,450	$ 5,047				$ 1,700
Shares Authorized For Equity Offering Program															15,000,000
Maximum percentage of Gross sale price per share compensation to sales agents															2.00%
Number Of Shares Sold By Company															6,421,553
Average Sales Price Per Share															$ 12.50
Additional shares Expected to be purchased under program		500,000