Investments in Unconsolidated Entities and International Investments - Combined Balance Sheets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
ASSETS:
Investment properties, at cost	$ 37,786,371	$ 38,050,196
Less - accumulated depreciation	14,881,480	14,891,937
Investment properties, at cost, net	22,904,891	23,158,259
Cash and cash equivalents	935,837	1,011,613
Tenant receivables and accrued revenue, net	1,016,902	1,236,734
Right-of-use assets, net	510,642	512,914
Deferred costs and other assets	1,098,004	1,082,168
Total assets	34,411,504	34,786,846
Liabilities and Partners' Deficit:
Mortgages and unsecured indebtedness	26,156,520	26,723,361
Accounts payable, accrued expenses, intangibles, and deferred revenues	1,195,851	1,311,925
Lease liabilities	513,351	515,492
Other liabilities	463,458	513,515
Total liabilities	30,383,970	31,128,608
Preferred units	511,698	185,892
Total liabilities and equity	$ 34,411,504	34,786,846
Unconsolidated properties | Maximum
Our Share of:
Estimated life of investment property	40 years
Equity Method Investees excluding HBS, Klepierre, TRG, ABG, Forever 21, J.C. Penny, RGG and SPARC Group | Unconsolidated properties
ASSETS:
Investment properties, at cost	$ 19,868,597	20,079,476
Less - accumulated depreciation	7,986,377	8,003,863
Investment properties, at cost, net	11,882,220	12,075,613
Cash and cash equivalents	1,295,486	1,169,422
Tenant receivables and accrued revenue, net	621,516	749,231
Right-of-use assets, net	172,089	185,598
Deferred costs and other assets	383,197	380,087
Total assets	14,354,508	14,559,951
Liabilities and Partners' Deficit:
Mortgages and unsecured indebtedness	15,462,903	15,569,485
Accounts payable, accrued expenses, intangibles, and deferred revenues	892,461	969,242
Lease liabilities	175,427	188,863
Other liabilities	404,662	426,321
Total liabilities	16,935,453	17,153,911
Preferred units	67,450	67,450
Partners' deficit	(2,648,395)	(2,661,410)
Total liabilities and equity	14,354,508	14,559,951
Our Share of:
Partners' deficit	(1,135,196)	(1,130,713)
Add: Excess Investment	1,332,392	1,399,757
Our net Investment in unconsolidated entities, at equity	$ 197,196	$ 269,044