Tax Credit Transactions (Details) (USD $)	12 Months Ended							12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Historic Tax Credit Transaction [Member]	Dec. 31, 2012 Historic Tax Credit Transaction [Member]	Dec. 31, 2011 Historic Tax Credit Transaction [Member]	Nov. 17, 2008 Historic Tax Credit Transaction [Member] sqft	Dec. 31, 2013 New Markets Tax Credit Transaction [Member]	Dec. 31, 2013 Brandywine Realty Trust [Member] New Markets Tax Credit Transaction [Member]	Dec. 31, 2012 Brandywine Realty Trust [Member] New Markets Tax Credit Transaction [Member]	Dec. 31, 2013 USB [Member] Historic Tax Credit Transaction [Member]	Dec. 31, 2012 USB [Member] Historic Tax Credit Transaction [Member]	Aug. 27, 2010 USB [Member] Historic Tax Credit Transaction [Member]	Dec. 31, 2013 USB [Member] New Markets Tax Credit Transaction [Member]	Dec. 31, 2012 USB [Member] New Markets Tax Credit Transaction [Member]
Tax Credit Transactions (Textuals) [Abstract]
Area of IRS Philadelphia Campus building (in square foot)							862,692
Percentage of building leased to IRS							100.00%
Agreed contribution in project cost by USB													$ 64,100,000
Amount received in advance for project cost	0	0	2,694,000
Tax credit conditions				20% recapture per year beginning one year after the completion of the IRS Philadelphia Campus				100% recapture for a period of seven years as provided in the Internal Revenue Code
Percentage of tax credit recapture				20.00%				100.00%
USB contributions presented within deferred income											26,800,000	39,100,000		13,300,000	13,300,000
Contribution allocated in non controlling interest				2,800,000	2,600,000
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period				over the five year credit recapture period as defined in the Internal Revenue Code
Historic tax credit transaction income	(11,853,000)	(11,840,000)	(12,026,000)	11,900,000
Allocated expenses within other income (expense)				500,000							500,000
Deferred transaction costs	122,954,000	122,243,000		1,000,000	1,600,000				5,300,000	5,300,000
Rate of return on noncontrolling interest expected				2.00%
Accretion of non-controlling interest liability				$ 1,400,000	$ 1,300,000	$ 1,300,000
Limit on tax credit claims under the Community Renewal Tax Relief	up to 39% of qualified investments in qualified, active low-income businesses or ventures
Percentage of qualified investments								39.00%
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period in years				5 years				7 years