Investments in Unconsolidated Entities and International Investments - Combined Balance Sheets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
ASSETS:
Investment properties, at cost	$ 37,984,645	$ 38,050,196
Less - accumulated depreciation	15,410,030	14,891,937
Investment properties, at cost, net	22,574,615	23,158,259
Cash and cash equivalents	438,423	1,011,613
Tenant receivables and accrued revenue, net	935,053	1,236,734
Right-of-use assets, net	506,236	512,914
Deferred costs and other assets	1,105,736	1,082,168
Total assets	33,946,139	34,786,846
Liabilities and Partners' Deficit:
Mortgages	25,584,372	26,723,361
Accounts payable, accrued expenses, intangibles, and deferred revenues	1,324,603	1,311,925
Lease liabilities	509,071	515,492
Other liabilities	525,361	513,515
Total liabilities	29,518,422	31,128,608
Preferred units	553,025	185,892
Total liabilities and equity	33,946,139	34,786,846
Unconsolidated properties | Equity Method Investees excluding HBS, Klepierre, TRG, ABG, Forever 21, J.C. Penny, RGG and SPARC Group
ASSETS:
Investment properties, at cost	19,867,502	20,079,476
Less - accumulated depreciation	8,287,531	8,003,863
Investment properties, at cost, net	11,579,971	12,075,613
Cash and cash equivalents	1,368,859	1,169,422
Tenant receivables and accrued revenue, net	567,034	749,231
Right-of-use assets, net	161,758	185,598
Deferred costs and other assets	415,768	380,087
Total assets	14,093,390	14,559,951
Liabilities and Partners' Deficit:
Mortgages	15,311,572	15,569,485
Accounts payable, accrued expenses, intangibles, and deferred revenues	854,603	969,242
Lease liabilities	165,334	188,863
Other liabilities	405,134	426,321
Total liabilities	16,736,643	17,153,911
Preferred units	67,450	67,450
Partners' deficit	(2,710,703)	(2,661,410)
Total liabilities and equity	14,093,390	14,559,951
Our Share of:
Partners' deficit	(1,161,814)	(1,130,713)
Add: Excess Investment	1,300,242	1,399,757
Our net Investment in unconsolidated entities, at equity	$ 138,428	$ 269,044
Unconsolidated properties | Maximum
Our Share of:
Estimated life of investment property	40 years