Beneficial Interest in Debt and Interest Expense (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Debt Instrument [Line Items]
Notes Payable, Gross of Notes Payable Held for Sale	$ 2,637,941,000		$ 2,637,941,000
Line of Credit Facility, Expiration Date			Apr. 01, 2016
At 100% [Abstract]
Debt, consolidated subsidiaries at 100%	2,015,999,000		2,015,999,000		3,058,053,000
Debt, unconsolidated joint ventures at 100%	1,785,602,000		1,785,602,000		1,551,161,000
Capitalized interest, consolidated subsidiaries at 100%			18,844,000	11,511,000
Capitalized interest, unconsolidated joint ventures @100%			2,836,000	73,000
Interest expense, consolidated subsidiaries at 100%	23,382,000	32,515,000	74,946,000	99,589,000
Interest Expense, Unconsolidated Joint Ventures, at 100%			55,065,000	51,578,000
Other Restrictions on Payment of Dividends			0.95
Restricted cash (Note 5)	43,258,000		43,258,000		5,046,000
Cash in escrow related to construction projects			39,600,000
At beneficial interest [Abstract]
Debt Consolidated Subsidiaries At Beneficial Interest	2,448,342,000		2,448,342,000		2,891,592,000
Debt, unconsolidated joint ventures at beneficial interest	984,512,000		984,512,000		868,942,000
Capitalized interest, consolidated subsidiaries at beneficial interest			18,136,000	11,169,000
Capitalized Interest, Unconsolidated Joint Ventures at Beneficial Interest			1,430,000	46,000
Interest expense, consolidated subsidiaries at beneficial interest			68,687,000	93,049,000
Interest expense, unconsolidated joint ventures at beneficial interest	10,006,000	9,415,000	29,805,000	28,192,000
The Mall at University Town Center [Member]
Debt Instrument [Line Items]
Construction Loan	155,600,000		155,600,000
Unconditional Guaranty Liability, Principal Balance, Percent	25.00%		25.00%
Interest Payable	200,000		200,000
At beneficial interest [Abstract]
Unconditional Guaranty Liability Upon Achievement of Performance Inventives, Principal Balance, Percent,	12.50%		12.50%
Unconditional Guaranty Liability, Interest, Percent	50.00%		50.00%
Construction Facility, Maximum Borrowing Capacity	225,000,000		225,000,000
Cherry Creek Shopping Center [Member]
Debt Instrument [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	50.00%		50.00%
International Plaza [Member]
Debt Instrument [Line Items]
Noncash Or Part Noncash, Acquisition Interest Sold			49.90%
Mall At Wellington Green [Member]
Debt Instrument [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	10.00%		10.00%
Mac Arthur Center Member
Debt Instrument [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	5.00%		5.00%
The Mall of San Juan [Member]
Debt Instrument [Line Items]
Construction Loan	116,000,000		116,000,000
Interest Payable	100,000		100,000
At beneficial interest [Abstract]
Debt Instrument, Interest Rate Terms			LIBOR plus 2.00%
Debt Instrument, Interest Rate Terms, Performance Contingency			LIBOR plus 1.75%
Number of Extension Options			two
Length Of Extension Option			one-year
Construction Facility, Maximum Borrowing Capacity	320,000,000		320,000,000
Term of Construction Facility, years			three
Stony Point [Member]
At 100% [Abstract]
Debt, consolidated subsidiaries at 100%	99,500,000		99,500,000
Secondary Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	65,000,000		65,000,000
Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,100,000,000		1,100,000,000
Starwood Transaction [Member]
Debt Instrument [Line Items]
Liabilities Held-for-Sale, Notes Payable	621,945,000		621,945,000
Liabilities Held-for-Sale, Notes Payable, At Beneficial Interest	$ 596,000,000		$ 596,000,000