Investments in Unconsolidated Real Estate Joint Ventures Unconsolidated Real Estate Joint Ventures (Details) (USD $)				6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Partnership Interest [Member]	Jun. 30, 2012 Houston [Member] SquareFeet	Jun. 30, 2012 Deer Park Warehouse [Member] SquareFeet	Jun. 30, 2012 Deer Park [Member] SquareFeet	Jun. 30, 2012 Wisconsin Dells [Member] SquareFeet	Jun. 30, 2012 National Harbor [Member] SquareFeet	Jun. 30, 2012 RioCan Canda [Member] SquareFeet	Jun. 30, 2012 Westgate [Member] SquareFeet	Jun. 30, 2012 Other [Member] SquareFeet
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				50.00%	33.30%	33.30%	50.00%	50.00%	50.00%	58.00%	50.00%
Square Footage of Real Estate Property				0	29,253	741,976	265,086	0	155,522	0	0
Equity Method Investments	$ 72,400,000	$ 28,500,000	$ 72,400,000	$ 21,000,000	$ 0	$ 4,100,000	$ 3,900,000	$ 900,000	$ 24,000,000	$ 18,300,000	$ 200,000
Joint Venture Debt	$ 273,000,000			$ 0	$ 1,800,000	$ 246,900,000	$ 24,300,000	$ 0	$ 0	$ 0	$ 0