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Summary of Significant Accounting Policies - Carrying Value of Long-Lived Assets and Investment in Unconsolidated Affiliates (Details)
3 Months Ended
Mar. 31, 2021
USD ($)
mall
other_property
Mar. 31, 2020
USD ($)
mall
other_property
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Impairment charges of real estate $ 57,182,000 $ 133,644,000
Number of malls with impairment | mall 3 2
Impairments of investments $ 0 $ 0
Malls    
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Impairment charges of real estate $ 57,182,000 $ 133,644,000
Number of malls with impairment | mall 3 2
Other Properties    
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Impairment charges of real estate $ 0 $ 0
Number of other properties with impairment | other_property 6 6