Investment in Unconsolidated Entities (Details 7) $ in Thousands		9 Months Ended
	May. 28, 2014 property	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Assets:
Investment properties at cost		$ 33,208,645	$ 31,318,532
Less - accumulated depreciation		9,664,911	8,950,747
Investment properties at cost, net		23,543,734	22,367,785
Cash and cash equivalents		856,861	612,282
Tenant receivables and accrued revenue, net		564,344	580,197
Deferred costs and other assets		1,394,174	1,806,789
Liabilities and Partners' Deficit:
Mortgages and other indebtedness		22,629,054	20,852,993
Accounts payable, accrued expenses, intangibles, and deferred revenues		1,307,707	1,259,681
Other liabilities		193,683	275,451
Total liabilities		25,495,387	23,555,288
Preferred units		43,815	44,062
Total liabilities and equity		30,641,303	29,532,330
Our Share of:
Our net investment in unconsolidated entities, at equity		2,480,603	2,378,800
Unconsolidated properties
Our Share of:
Number of properties merged under spin off into publicly traded REIT (Washington Prime Group Inc.) | property	10
Equity Method Investments. | Unconsolidated properties
Assets:
Investment properties at cost		16,998,613	16,087,282
Less - accumulated depreciation		5,745,006	5,457,899
Investment properties at cost, net		11,253,607	10,629,383
Cash and cash equivalents		854,397	993,178
Tenant receivables and accrued revenue, net		335,259	362,201
Investment in unconsolidated entities, at equity			11,386
Deferred costs and other assets		554,938	536,600
Total assets		12,998,201	12,532,748
Liabilities and Partners' Deficit:
Mortgages and other indebtedness		13,932,542	13,272,557
Accounts payable, accrued expenses, intangibles, and deferred revenues		951,901	1,015,334
Other liabilities		385,277	493,718
Total liabilities		15,269,720	14,781,609
Preferred units		67,450	67,450
Partners' deficit		(2,338,969)	(2,316,311)
Total liabilities and equity		12,998,201	12,532,748
Our Share of:
Partners' deficit		(875,336)	(663,700)
Add: Excess investment		1,809,694	1,875,337
Our net investment in unconsolidated entities, at equity		$ 934,358	$ 1,211,637
Equity Method Investments. | Unconsolidated properties | Maximum
Our Share of:
Life of joint ventures with excess investment		40 years