Investments in Unconsolidated Entities and International Investments - Combined Balance Sheets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Our Share of:
Investment in Klepierre, at equity	$ 1,614,109	$ 1,769,488
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	$ 19,259,601	18,807,449
Less - accumulated depreciation	7,263,363	6,834,633
Investment properties at cost, net	11,996,238	11,972,816
Cash and cash equivalents	880,648	1,076,398
Tenant receivables and accrued revenue, net	475,710	445,148
Deferred costs and other assets	581,435	390,818
Total assets	13,934,031	13,885,180
Liabilities and Partners' Deficit:
Mortgages	15,217,266	15,235,415
Accounts payable, accrued expenses, intangibles, and deferred revenue	942,250	976,311
Other liabilities	521,518	344,205
Total liabilities	16,681,034	16,555,931
Preferred units	67,450	67,450
Partners' deficit	(2,814,453)	(2,738,201)
Total liabilities and partners' deficit	13,934,031	13,885,180
Our Share of:
Partners' deficit	(1,227,239)	(1,168,216)
Add: Excess Investment	1,540,770	1,594,198
Investment in Klepierre, at equity	$ 313,531	$ 425,982