Combined Guarantor Subsidiaries - Organization and Basis of Presentation - Narrative (Details)	Sep. 30, 2019 USD ($) associated_center mall subsidiary state mortgage_note_receivable senior_unsecured_note	Jan. 01, 2019 USD ($)
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of states in which entity operates | state	26
Number of malls securing the credit facility | mall	17
Number of associated centers securing the credit facility | associated_center	3
Number of wholly owned subsidiaries | subsidiary	36
Guarantor Subsidiaries
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of states in which entity operates | state	26
Number of malls securing the credit facility | mall	17
Number of associated centers securing the credit facility | associated_center	3
Number of wholly owned subsidiaries | subsidiary	36
Number of malls not classified as collateral for the secured credit facility | mall	5
Number of associated centers not classified as collateral for the secured credit facility | associated_center	2
Number of mortgage notes receivable not classified as collateral for the secured credit facility | mortgage_note_receivable	4
Line of Credit | Secured Debt
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Balance of Non-recourse Debt | $		$ 1,185,000,000
Line of Credit | Secured Debt | Guarantor Subsidiaries
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Balance of Non-recourse Debt | $	$ 1,185,000,000	$ 1,185,000
Senior Unsecured Notes | Guarantor Subsidiaries
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Balance of Non-recourse Debt | $	$ 1,375,000,000
Number of debt instruments | senior_unsecured_note	3