Investment in Unconsolidated Entities - Balance Sheets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Our Share of:
Our net Investment in unconsolidated entities, at equity	$ 2,439,554	$ 2,481,574
Unconsolidated properties
Assets:
Investment properties, at cost	17,500,339	17,186,884
Less - accumulated depreciation	5,890,642	5,780,261
Investment properties at cost, net	11,609,697	11,406,623
Cash and cash equivalents	787,140	818,805
Tenant receivables and accrued revenue, net	339,807	354,133
Deferred costs and other assets	356,659	482,024
Total assets	13,093,303	13,061,585
Liabilities and Partners' Deficit:
Mortgages	14,117,650	13,827,215
Accounts payable, accrued expenses, intangibles, and deferred revenues	871,497	985,159
Other liabilities	384,632	468,005
Total liabilities	15,373,779	15,280,379
Preferred units	67,450	67,450
Partners' deficit	(2,347,926)	(2,286,244)
Total liabilities and equity	13,093,303	13,061,585
Our Share of:
Partners' deficit	(990,453)	(854,562)
Add: Excess Investment	1,828,949	1,788,749
Our net Investment in unconsolidated entities, at equity	$ 838,496	$ 934,187
Unconsolidated properties | Maximum
Our Share of:
Life of joint ventures with excess investment	40 years