Investments in Unconsolidated Real Estate Joint Ventures (Unconsolidated Real Estate Joint Ventures) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014 sqft		Dec. 31, 2013 sqft	May 30, 2013
Schedule of Equity Method Investments [Line Items]
Carrying Value of Investment (in millions)	$ 210.1		$ 140.2
Total Joint Venture Debt (in millions)	214.6		202.7
Partnership Interest [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value of Investment (in millions)	210.1		140.2
Charlotte [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%		50.00%	50.00%
Square Feet	0		0
Carrying Value of Investment (in millions)	30.8		11.6
Total Joint Venture Debt (in millions)	0		0
Galveston/Houston [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%		50.00%
Square Feet	353,000		353,000
Carrying Value of Investment (in millions)	6.7		7.4
Total Joint Venture Debt (in millions)	65.0		65.0
National Harbor [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%		50.00%
Square Feet	339,000		336,000
Carrying Value of Investment (in millions)	19.3		16.7
Total Joint Venture Debt (in millions)	62.0		52.4
RioCan Canda [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%		50.00%
Square Feet	432,000		433,000
Carrying Value of Investment (in millions)	101.4		85.7
Total Joint Venture Debt (in millions)	17.5		17.9
Savannah [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%	[1]
Square Feet	0	[1]
Carrying Value of Investment (in millions)	33.1	[1]
Total Joint Venture Debt (in millions)	0	[1]
Westgate [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	58.00%		58.00%
Square Feet	332,000		332,000
Carrying Value of Investment (in millions)	15.7		16.1
Total Joint Venture Debt (in millions)	45.8		43.1
Wisconsin Dells [Member]
Schedule of Equity Method Investments [Line Items]
Ownership %	50.00%		50.00%
Square Feet	265,000		265,000
Carrying Value of Investment (in millions)	2.4		2.5
Total Joint Venture Debt (in millions)	24.3		24.3
Other [Member]
Schedule of Equity Method Investments [Line Items]
Square Feet	0		0
Carrying Value of Investment (in millions)	0.7		0.2
Total Joint Venture Debt (in millions)	$ 0		$ 0

[1] Based on capital contribution and distribution provisions in the joint venture agreement, we expect our economic interest in the venture's cash flow to be greater than the ownership percentage indicated above, which in this case, states our legal interest in this venture. Our economic interest may fluctuate based on a number of factors, including mortgage financing, partnership capital contributions and distributions, and proceeds from gains or losses of asset sales.