Acquisition of Rental Property Acquisition of Rental Property (Details) (USD $)	9 Months Ended	3 Months Ended
	Sep. 30, 2011	Sep. 30, 2011 Prime Outlets at Jeffersonville [Member] SquareFeet	Sep. 30, 2011 Atlantic City and Ocean City [Member]	Sep. 30, 2011 Atlantic City Outlets The Walk [Member] SquareFeet outletcenters	Sep. 30, 2011 Ocean City Factory Outlets [Member] SquareFeet	Sep. 30, 2011 The Outlets at Hershey [Member]
Acquistion of Rental Property [Line Items]
Business Combination, Acquisition Related Costs		$ 2,519,000,000
Business Acquisition, Effective Date of Acquisition		June 28, 2011	July 15, 2011			September 30, 2011
Business Acquisition, Purchase Price Allocation, Liabilities Assumed			73,500,000			31,400,000
Business Acquisition, Cost of Acquired Entity, Purchase Price			183,500,000			49,800,000
Business Acquisition, Cost of Acquired Entity, Cash Paid	134,000,000		110,000,000			18,400,000
Square Footage of Real Estate Property		410,000		491,000	200,000
Notes Receivable, Related Parties						6,200,000
Number of Stores				100	40
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	7,880,000,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	$ (221,000)