Investments in Unconsolidated Joint Ventures (Details) (USD $) In Billions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Equity method investment, difference between carrying amount and underlying equity [Abstract]
Depreciable Basis In Years	40 years
Equity of certain joint ventures	less than zero
Fair Value Of Unconsolidated Joint Ventures Notes Payable	$ 1.5	$ 1.5
Arizona Mills [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.00%	50.00%
Fair Oaks [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.00%	50.00%
The Mall at Millenia [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.00%	50.00%
Stamford Town Center [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.00%	50.00%
Sunvalley [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.00%	50.00%
Waterside Shops [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.00%	50.00%
Westfarms [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	79.00%	79.00%