Investments in Unconsolidated Entities and International Investments - Unconsolidated Entity Transactions (Details) $ / shares in Units, $ in Thousands								3 Months Ended		12 Months Ended			20 Months Ended
	Sep. 25, 2018 $ / shares shares	Jun. 07, 2018 USD ($)	Nov. 03, 2017 USD ($) store	Sep. 15, 2016 item	Apr. 14, 2016 USD ($)	Apr. 05, 2016 USD ($)	Apr. 13, 2015 property	Dec. 31, 2018 USD ($) property	Jun. 30, 2017 USD ($)	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($) property	May 31, 2017
Investment in Unconsolidated Entities
Insurance proceeds recorded as business interruption										$ 19,083
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net										288,827	$ 3,647	$ 84,553
Gain on interest in unconsolidated entities										35,621
Share of net income, net of amortization of our excess investment										475,250	400,270	353,334
Investment properties, at cost								$ 37,092,670		37,092,670	36,393,464		$ 37,092,670
Distributions of income from unconsolidated entities										$ 390,137	374,101	331,627
Outlets at Orange
Investment in Unconsolidated Entities
Ownership interests acquired (as a percent)	50.00%
Ownership interest after acquisition (as a percent)								100.00%		100.00%			100.00%
Simon Property Group, L.P.
Investment in Unconsolidated Entities
Insurance proceeds recorded as business interruption										$ 19,083
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net										288,827	3,647	84,553
Gain on interest in unconsolidated entities										35,621
Share of net income, net of amortization of our excess investment										475,250	400,270	353,334
Investment properties, at cost								$ 37,092,670		37,092,670	36,393,464		$ 37,092,670
Distributions of income from unconsolidated entities										390,137	$ 374,101	$ 331,627
Simon Property Group, L.P. | Outlets at Orange
Investment in Unconsolidated Entities
Number of units issued in connection with acquisition of the remaining interest in orange outlet | shares	475,183
Business acquisition price (in dollars per share) | $ / shares	$ 176.99
Colorado Mills
Investment in Unconsolidated Entities
Impairment charges									$ 32,500
Insurance proceeds recorded as business interruption													$ 65,900
Gain on business interruption										$ 33,400
Aventura Mall
Investment in Unconsolidated Entities
Loan defeasance charge		$ 30,900
Write off of deferred debt issuance cost		6,500
Mortgages | Aventura Mall
Investment in Unconsolidated Entities
Debt refinanced		1,200,000
Construction loan | Aventura Mall
Investment in Unconsolidated Entities
Debt refinanced		200,800
4.12% fixed interest rate mortgage maturing July 2028 | Aventura Mall
Investment in Unconsolidated Entities
Debt issued		$ 1,750,000
Fixed interest rate (as a percent)		4.12%
The Shops at Crystals
Investment in Unconsolidated Entities
Ownership interest (as a percent)					50.00%
Payments to acquire equity method investment					$ 1,100,000
The Shops at Crystals | 3.74% fixed-rate mortgage maturing July 2026
Investment in Unconsolidated Entities
Debt issued					$ 550,000
Fixed interest rate (as a percent)					3.74%
Quaker Bridge Mall
Investment in Unconsolidated Entities
Ownership interest (as a percent)						50.00%
Quaker Bridge Mall | 4.50% fixed-rate mortgage maturing May 2026
Investment in Unconsolidated Entities
Debt issued						$ 180,000
Fixed interest rate (as a percent)						4.50%
Distributions of income from unconsolidated entities						$ 180,000
Sears Joint Venture | Sears
Investment in Unconsolidated Entities
Number of stores at malls with previously owned interest | property							10
Seritage Growth Properties
Investment in Unconsolidated Entities
Ownership interest (as a percent)								50.00%		50.00%			50.00%
Number of stores in which additional interest was acquired | store			12
Number of stores at malls with previously owned interest | store			5
Investment properties, at cost			$ 149,100
Aventura Mall
Investment in Unconsolidated Entities
Ownership interest (as a percent)		33.30%
Share of early debt repayment charge		$ 12,500
Colorado Mills
Investment in Unconsolidated Entities
Ownership interest (as a percent)														37.50%
Gain upon acquisition of controlling interests, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net										$ 12,500
Aeropostale
Investment in Unconsolidated Entities
Number of joint ventures | item				2
Aeropostale Retail Operations
Investment in Unconsolidated Entities
Ownership interest (as a percent)								44.95%		44.95%			44.95%
Authentic Brands Group LLC
Investment in Unconsolidated Entities
Ownership interest (as a percent)								5.40%		5.40%			5.40%
Gain on interest in unconsolidated entities										$ 35,600
HBS
Investment in Unconsolidated Entities
Ownership interest (as a percent)								11.70%		11.70%	11.70%		11.70%
Share of net income, net of amortization of our excess investment										$ 15,100	$ 16,100
Total assets								$ 1,700,000		1,700,000			$ 1,700,000
Total liabilities								$ 834,100		834,100			$ 834,100
Total revenues										326,300	351,000
Total operating income										196,300	313,800
Consolidated net income										$ 105,900	$ 220,200
HBS | United States
Investment in Unconsolidated Entities
Number of properties owned | property								42		42	42		42
HBS | Germany
Investment in Unconsolidated Entities
Number of properties owned | property											41
Gain on sale or disposal of assets and interests in unconsolidated entities, net								$ 91,100