Investments in Unconsolidated Entities and International Investments - Unconsolidated Entity Transactions (Details) $ / shares in Units, $ in Thousands						1 Months Ended	3 Months Ended			6 Months Ended
	Jun. 01, 2021 USD ($)	Dec. 29, 2020 USD ($) property $ / shares shares	Dec. 07, 2020 USD ($)	Feb. 19, 2020 USD ($) item	Sep. 15, 2016 item	Jan. 31, 2020 USD ($)	Jun. 30, 2021 USD ($) property	Mar. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) property	Jun. 30, 2020 USD ($)	Jul. 01, 2021	Dec. 31, 2020 USD ($)
Investment in Unconsolidated Entities
Payments for acquisitions										$ 157,080	$ 107,797
Income from unconsolidated entities							$ 348,545		$ 44,322	363,614	94,787
Total revenue							1,254,146		1,062,041	2,494,097	2,415,401
Operating Income							604,723		450,868	1,209,334	1,105,737
Consolidated net income							705,869		290,548	1,216,329	795,952
Simon Property Group, L.P.
Investment in Unconsolidated Entities
Payments for acquisitions										157,080	107,797
Income from unconsolidated entities							348,545		44,322	363,614	94,787
Total revenue							1,254,146		1,062,041	2,494,097	2,415,401
Operating Income							604,723		450,868	1,209,334	1,105,737
Consolidated net income							$ 705,869		290,548	$ 1,216,329	$ 795,952
TRG
Investment in Unconsolidated Entities
Ownership interest (as a percent)		80.00%					80.00%			80.00%
Share price (in dollars per share) | $ / shares		$ 43.00
Payments for acquisitions		$ 3,500,000
Impairment charge to reduce investment to its estimated fair value							$ 31,600			$ 63,100
Income from unconsolidated entities							(13,700)			(38,500)
Total revenue										271,600
Operating Income										85,400
Consolidated net income										30,100
Aggregate investment in ventures							3,415,996			3,415,996			$ 3,451,897
TRG | Series J Cumulative Preferred Shares
Investment in Unconsolidated Entities
Redemption of preferred shares		$ 192,500
Preferred stock stated dividend rate (as a percent)		6.50%
TRG | Series K Cumulative Preferred Shares
Investment in Unconsolidated Entities
Redemption of preferred shares		$ 170,000
Preferred stock stated dividend rate (as a percent)		6.25%
TRG | Series A Cumulative Preferred Shares
Investment in Unconsolidated Entities
Preferred stock stated dividend rate (as a percent)		6.38%
Issuance of preferred units		$ 362,500
TRG | Simon Property Group, L.P.
Investment in Unconsolidated Entities
Number of units issued in connection with acquisition | shares		955,705
Aggregate investment in ventures							$ 3,415,996			$ 3,415,996			$ 3,451,897
TRG | TRG
Investment in Unconsolidated Entities
Number of regional, super regional and outlet malls | property		24					24			24
Eddie Bauer
Investment in Unconsolidated Entities
Ownership interest (as a percent)	49.00%
Payments for acquisitions	$ 100,800
J.C. Penny Department Store
Investment in Unconsolidated Entities
Ownership interest (as a percent)			41.67%
Payments for acquisitions			$ 125,000
Forever 21
Investment in Unconsolidated Entities
Ownership interest (as a percent)								50.00%
Payments for acquisitions								$ 56,300
Number of joint ventures | item				2
Aggregate investment in ventures				$ 67,600
Bargain purchase gain									$ 35,000
Additional noncontrolling interest purchased								12.50%
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%
Payments for acquisitions						$ 6,700
Additional noncontrolling interest purchased						5.05%
Authentic Brands Group LLC
Investment in Unconsolidated Entities
Ownership interest (as a percent)							6.60%			6.60%
Payments for acquisitions						$ 33,500
Additional noncontrolling interest purchased						1.37%
ABG
Investment in Unconsolidated Entities
Ownership interest (as a percent)												11.00%
Multi family residential property
Investment in Unconsolidated Entities
Proceeds from sale or disposal of real estate assets							$ 27,100
Gain (loss) on disposition of interest in properties							$ 14,900