Investments in Unconsolidated Real Estate Joint Ventures Unconsolidated Real Estate Joint Ventures (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 82.7	$ 28.5
Joint Venture Debt	288.9
Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	82.7
Houston [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Area of Real Estate Property	352,705
Equity Method Investments	28.5
Joint Venture Debt	0
Deer Park Warehouse [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.30%
Area of Real Estate Property	29,253
Equity Method Investments	0
Joint Venture Debt	1.8
Deer Park [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.30%
Area of Real Estate Property	741,981
Equity Method Investments	3.5
Joint Venture Debt	246.9
Wisconsin Dells [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Area of Real Estate Property	265,086
Equity Method Investments	3.9
Joint Venture Debt	24.3
National Harbor [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Area of Real Estate Property	0
Equity Method Investments	1.2
Joint Venture Debt	0
RioCan Canda [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Area of Real Estate Property	155,522
Equity Method Investments	25.9
Joint Venture Debt	0
Westgate [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	58.00%
Area of Real Estate Property	0
Equity Method Investments	19.5
Joint Venture Debt	15.9
Other [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage
Area of Real Estate Property	0
Equity Method Investments	0.2
Joint Venture Debt	$ 0