Investment in Unconsolidated Entities (Details 3)	3 Months Ended		9 Months Ended			0 Months Ended	6 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended		0 Months Ended
	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)	Mar. 14, 2012 Klepierre USD ($)	Sep. 30, 2012 Klepierre USD ($)	Sep. 30, 2013 Klepierre USD ($)	Sep. 30, 2013 McArthurGlen Group USD ($)	Jun. 30, 2013 McArthurGlen Group Minimum Item	Sep. 30, 2013 Europe Klepierre USD ($)	Mar. 14, 2012 Europe Klepierre USD ($)	Oct. 16, 2013 Europe McArthurGlen Group USD ($) property	Oct. 16, 2013 Europe McArthurGlen Group EUR (€)	Oct. 16, 2013 Europe McArthurGlen Group Minimum	Oct. 16, 2013 Europe McArthurGlen Group Maximum	Sep. 30, 2013 Europe McArthurGlen Group Ashford Designer Outlets	Sep. 30, 2013 Europe McArthurGlen Group Property management and development companies	Sep. 30, 2013 Canada McArthurGlen Group Development project
Schedule of Equity Method Investments
Shares owned											57,634,148
Joint venture ownership percentage						28.70%					28.90%				60.00%	90.00%	22.50%	50.00%	45.00%
Quoted market price per share (in dollars per share)											$ 43.25
Excess investment												$ 1,200,000,000
Share of net income, net of amortization of our excess investment	47,916,000	37,129,000	158,663,000	96,613,000			4,700,000				23,800,000
Total revenues											1,100,000,000
Total operating income											538,600,000
Consolidated net Income								231,500,000
Equity investment	1,991,900,000		1,991,900,000		2,108,966,000				73,900,000
Number of joint ventures to invest in per definitive agreement										1
Number of outlets in which interest acquired													4	4
Purchase price of business acquired						$ 2,000,000,000							$ 441,100,000	€ 327,500,000