Investments in and Advances to Unconsolidated Affiliates - Core Portfolio - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 04, 2021	Dec. 31, 2020	Sep. 30, 2021	Apr. 01, 2020
Schedule of Equity Method Investments [Line Items]
Cost method investments		$ 1,881	$ 3,176
Riverdale
Schedule of Equity Method Investments [Line Items]
Repayment related to mortgage	$ 7,900
Recognized gain in shares amount	600
Proceeds from sale of property	10,500
Mervyns II
Schedule of Equity Method Investments [Line Items]
Cost method investments			$ 1,200
Core Portfolio | Fifth Wall Ventures Retail Fund, L.P.
Schedule of Equity Method Investments [Line Items]
Cost method investments	1,300			$ 400
Impairment of investments		$ 400
Core Portfolio | Brandywine Portfolio
Schedule of Equity Method Investments [Line Items]
Cost method investment ownership percentage				24.78%
Note receivable exchanged	$ 38,700
Note receivable accrued interest				$ 2,000
Equity method investment, controlling interest percentage				100.00%