Investments in and Advances To Joint Ventures (Details Textuals) (USD $)	3 Months Ended					9 Months Ended
	Sep. 30, 2011 ReportableSegment sqft Property Store Loan	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2010 ReportableSegment Property sqft	Dec. 31, 2009	Sep. 30, 2011 Year Entity Property ReportableSegment sqft Store Loan	Sep. 30, 2010 Entity sqft Property ReportableSegment	Dec. 31, 2010 Store Property Loan
Schedule of Equity Method Investments [Line Items]
Company's ownership interest		50.00%
Equity Investments in Joint Ventures (Textuals) [Abstract]
Number of shopping center properties owned under various unconsolidated joint ventures	231					231		236
Company's proportionate share of impairment charges were recorded on four assets being marketed for sale	$ 6,200,000					$ 6,200,000
Company's aggregate impairment charges reclassified to discontinued operations				8,800,000			19,700,000
Company's proportionate share of gain on disposition of assets by unconsolidated joint ventures						10,500,000
Impairment charges	51,245,000				170,900,000	68,457,000	59,277,000
Number of properties sold under disposition of discontinued operations by unconsolidated joint ventures				4		3	25
Number of unconsolidated joint ventures who disposed of their discontinued operations						3	4
Company's proportionate share of loss on disposition of assets by unconsolidated joint ventures				2,800,000			4,100,000
Ownership Interest in Other Joint Venture			50.00%
Percentage of Annual Interest Rate for Advances To Joint Ventures, Minimum						10.50%
Percentage of Annual Interest Rate for Advances To Joint Ventures, Maximum						12.00%
Bloomfield Loan advance, including accrued interest	66,900,000					66,900,000
Accrued Interest on Bloomfield Loan advance	8,800,000					8,800,000
Reserve associated with construction loan		1,600,000
Construction loan to Joint Ventures		4,300,000
Proceeds from the sale of shopping center asset		50,300,000				50,300,000
Company's proportionate share of gain		12,600,000				12,600,000
Interest rate on the Bloomfield Loan	greater of LIBOR plus 700 basis points or 12% and a default rate of 16%					greater of LIBOR plus 700 basis points or 12% and a default rate of 16%
Gain Recorded By Joint Venture		22,800,000				22,800,000
Unconsolidated Joint Ventures [Member]
Equity Investments in Joint Ventures (Textuals) [Abstract]
Impairment charges	63,041,000			65,000		63,041,000	65,000
Sonae Sierra Brasil [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds From Initial Public Offering			280,000,000
Company's ownership interest			50.00%
Percentage of Effective Ownership Before Initial Public Offering						48.00%
Percentage of Effective Ownership After Initial Public Offering						33.00%
Company's share of loan repayment proceeds			$ 22,400,000