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	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	$ 41,413	$ 55,988	$ 42,788
Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	24,400	30,000	17,100
Asset and Property Management Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	31,255	42,355	31,751
Asset and Property Management Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	18,400	21,700	12,900
Leasing Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	5,528	6,300	6,380
Leasing Commissions [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	2,800	3,100	1,100
Disposition Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	3,142	3,454	2,959
Disposition Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	3,100	3,300	3,000
Credit Facility Guaranty and Refinancing Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	60	1,860	60
Credit Facility Guaranty and Refinancing Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	$ 100	$ 1,900	$ 100