Investments in Unconsolidated Entities and International Investments - Combined Balance Sheets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Our Share of:
Investment in unconsolidated entities, at equity	$ 2,220,414	$ 2,266,483
Unconsolidated properties | Maximum
Our Share of:
Estimated life of investment property	40 years
Equity Method Investees excluding Klepierre, Aeropostale, ABG and HBS | Unconsolidated properties
Assets:
Investment properties, at cost	$ 18,807,449	18,328,747
Less - accumulated depreciation	6,834,633	6,371,363
Investment properties at cost, net	11,972,816	11,957,384
Cash and cash equivalents	1,076,398	956,084
Tenant receivables and accrued revenue, net	445,148	403,125
Deferred costs and other assets	390,818	355,585
Total assets	13,885,180	13,672,178
Liabilities and Partners' Deficit:
Mortgages	15,235,415	14,784,310
Accounts payable, accrued expenses, intangibles, and deferred revenues	976,311	1,033,674
Other liabilities	344,205	365,857
Total liabilities	16,555,931	16,183,841
Preferred units	67,450	67,450
Partners' deficit	(2,738,201)	(2,579,113)
Total liabilities and partners' deficit	13,885,180	13,672,178
Our Share of:
Partners' deficit	(1,168,216)	(1,144,620)
Add: Excess Investment	1,594,198	1,733,063
Investment in unconsolidated entities, at equity	$ 425,982	$ 588,443