Interim Financial Statements (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2019 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2019 USD ($) $ / shares	Jun. 25, 2020 Rate	Feb. 09, 2020 $ / shares Rate	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 4,919,000
Noncontrolling Interest, Ownership Percentage by Parent Company	70.00%		70.00%
Number of urban and suburban shopping centers in the Company's owned portfolio	24		24
Number of states in which Company operates	11		11
Simon Property Group, Inc. transaction costs	$ 9,060,000		$ 15,445,000
Operating Leases, Future Minimum Payments Receivable, Current	222,896,000		222,896,000
Operating Leases, Future Minimum Payments Receivable, in Two Years	414,533,000		414,533,000
Operating Leases, Future Minimum Payments Receivable, in Three Years	368,379,000		368,379,000
Operating Leases, Future Minimum Payments Receivable, in Four Years	325,500,000		325,500,000
Operating Leases, Future Minimum Payments Receivable, in Five Years	279,255,000		279,255,000
Operating Leases, Future Minimum Payments Receivable, Thereafter	678,910,000		678,910,000
Shopping Center and Other Operational Revenues	4,744,000	$ 11,993,000	16,762,000	23,555,000
Management Leasing And Development Services	824,000	892,000	1,390,000	2,108,000
Total revenue from contracts with customers	5,568,000	12,885,000	18,152,000	25,663,000
Restructuring Charges	0	84,000	362,000	709,000
Costs Associated With Shareowner Activism	$ 0	12,000,000	$ 0	16,000,000
Related Party Costs		$ 5,000,000		$ 5,000,000
Substantial Doubt about Going Concern, Management's Evaluation			When preparing financial statements for each annual and interim reporting period, management has the responsibility to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within one year after the date that the financial statements are issued. No such conditions or events were identified as of the issuance date of the financial statements contained in this Quarterly Report on Form 10-Q.
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interests			70.00%	70.00%
Westfarms [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	79.00%		79.00%				79.00%
International Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage (in hundredths)	50.10%		50.10%				50.10%
Series J Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Preferred Stock, Dividend Rate, Percentage			6.50%
Series K Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Preferred Stock, Dividend Rate, Percentage			6.25%
International Market Place [Member]
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent Company	93.50%		93.50%
Accumulated Distributions in Excess of Net Income [Member]
Schedule of Equity Method Investments [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 3,156,000
Accumulated Distributions in Excess of Net Income [Member] | Accounting Standards Update 2016-02 [Member]
Schedule of Equity Method Investments [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 3,200,000
Series K Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Preferred Stock, Dividends Per Share, Declared | $ / shares	$ 0.390625	$ 0.390625	$ 0.78125	$ 0.78125
Series J Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Preferred Stock, Dividends Per Share, Declared | $ / shares	$ 0.40625	$ 0.40625	$ 0.8125	$ 0.8125
Noncontrolling Interest [Member]
Schedule of Equity Method Investments [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 1,763,000
Noncontrolling Interest [Member] | Accounting Standards Update 2016-02 [Member]
Schedule of Equity Method Investments [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 1,800,000
Taubman Centers Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Business Acquisition, Ownership Percentage, Simon Operating Partnership | Rate						100.00%
Business Acquisition, Share Price | $ / shares						$ 52.50
Shareholders Voted in Favor of Merger Agreement - Percent of Shares Voted | Rate					99.70%
Shareholders Voted in Favor of Merger Agreement as a Percent of Shares Entitled to Vote | Rate					84.70%
TRG [Member]
Schedule of Equity Method Investments [Line Items]
Business Acquisition, Ownership Percentage, Simon Operating Partnership | Rate						80.00%
Business Acquisition, Ownership Percentage, Taubman Family | Rate						20.00%
Line of Credit [Member]
Schedule of Equity Method Investments [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,100,000,000		$ 1,100,000,000
Unsecured Debt 275M Term Loan [Member]
Schedule of Equity Method Investments [Line Items]
Unsecured Debt	275,000,000		275,000,000
Unsecured Debt 250M Term Loan [Member]
Schedule of Equity Method Investments [Line Items]
Unsecured Debt	$ 250,000,000		$ 250,000,000