Investments in Unconsolidated Real Estate Joint Ventures (Unconsolidated Real Estate Joint Ventures) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Carrying Value of Investment (in millions)	$ 162.1	$ 126.6
Joint Venture Debt Outstanding	336.3	325.2
Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value of Investment (in millions)	162.1	126.6
Deer Park [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	33.30%	33.30%
Square Feet	741,981	741,981
Carrying Value of Investment (in millions)	2.0	3.0
Joint Venture Debt Outstanding	246.9	246.9
Deer Park Warehouse [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %		33.30%
Square Feet		29,253
Carrying Value of Investment (in millions)		0
Joint Venture Debt Outstanding		1.9
Galveston/Houston [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet		352,705
Carrying Value of Investment (in millions)	40.1	36.7
Joint Venture Debt Outstanding	0	0
National Harbor [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet	0	0
Carrying Value of Investment (in millions)	17.3	2.6
Joint Venture Debt Outstanding	4.2	0
RioCan Canda [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet	434,162	434,562
Carrying Value of Investment (in millions)	82.3	62.2
Joint Venture Debt Outstanding	18.7	20.1
Westgate [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	58.00%	58.00%
Square Feet		332,234
Carrying Value of Investment (in millions)	16.8	19.1
Joint Venture Debt Outstanding	42.2	32.0
Wisconsin Dells [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	50.00%
Square Feet	265,086	265,086
Carrying Value of Investment (in millions)	2.5	2.8
Joint Venture Debt Outstanding	24.3	24.3
Other [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %
Square Feet	0	0
Carrying Value of Investment (in millions)	1.1	0.2
Joint Venture Debt Outstanding	$ 0	$ 0