Investments in Unconsolidated Entities and International Investments - Unconsolidated Entity Transactions (Details) $ in Thousands				1 Months Ended	3 Months Ended				9 Months Ended
	Feb. 19, 2020 USD ($) item	Oct. 16, 2019 USD ($)	Sep. 15, 2016 item	Jan. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) item	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Sep. 19, 2019
Investment in Unconsolidated Entities
Number of joint ventures with recorded other-than-temporary impairment | item					3
Aggregate investment in ventures					$ 1,641,680				$ 1,641,680		$ 1,731,649
Share of net income, net of amortization of our excess investment excluding impairment					61,823		$ 119,706		156,610	$ 316,691
Impairment charge to reduce investment to its estimated fair value					55,200
Total revenue					1,060,674		1,416,554		3,476,074	4,266,574
Operating Income					404,024		705,302		1,509,761	2,130,955
Consolidated Net Income					168,646		628,724		964,598	1,832,772
Hotel
Investment in Unconsolidated Entities
Ownership interests acquired (as a percent)												50.00%
Ownership interest after acquisition (as a percent)												100.00%
Simon Property Group, L.P.
Investment in Unconsolidated Entities
Aggregate investment in ventures					1,641,680				1,641,680		$ 1,731,649
Share of net income, net of amortization of our excess investment excluding impairment					61,823		119,706		156,610	316,691
Total revenue					1,060,674		1,416,554		3,476,074	4,266,574
Operating Income					404,024		705,302		1,509,761	2,130,955
Consolidated Net Income					$ 168,646		628,724		$ 964,598	1,832,772
Forever 21
Investment in Unconsolidated Entities
Number of joint ventures | item	2
Ownership interest (as a percent)	37.50%
Aggregate investment in ventures	$ 67,600
Bargain purchase gain						$ 35,000
Shop Premium Outlets
Investment in Unconsolidated Entities
Ownership interest (as a percent)		45.00%
Contribution to form joint venture		$ 276,800
SPARC Group
Investment in Unconsolidated Entities
Number of joint ventures | item			2
SPARC Group Retail Operations
Investment in Unconsolidated Entities
Ownership interest (as a percent)					50.00%				50.00%
Additional noncontrolling interest purchased				5.05%
Purchase of equity instruments				$ 6,700
Authentic Brands Group LLC
Investment in Unconsolidated Entities
Ownership interest (as a percent)					6.80%				6.80%
Additional noncontrolling interest purchased				1.37%
Purchase of equity instruments				$ 33,500
HBS
Investment in Unconsolidated Entities
Ownership interest (as a percent)					11.70%				11.70%		11.70%
Share of net income, net of amortization of our excess investment excluding impairment					$ 900		$ (5,200)		$ 1,900	$ (13,300)
Impairment charge to reduce investment to its estimated fair value					$ 36,100
Unconsolidated properties | Disposed by Sales | Residential properties
Investment in Unconsolidated Entities
Proceeds from sale or disposal of real estate assets								$ 17,300
Gain (loss) on disposition of interest in properties								$ 15,600