Investment in and Advances to Affiliate - Schedule of Revenue From Contracts With Customers Included in Fee and Other Income on Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	$ 12,901	$ 9,100	$ 28,964	$ 32,466
Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	9,500	5,600	19,400	18,800
Asset and Property Management Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	6,459	7,326	19,636	24,201
Asset and Property Management Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	3,600	4,400	11,500	14,100
Leasing Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	624	648	2,679	4,327
Leasing Commissions [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	300	300	1,700	2,000
Disposition Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	5,500	800	6,100	2,600
Credit Facility Guaranty [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	$ 100	$ 100	$ 100	$ 100