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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	$ 8,620	$ 14,398	$ 23,367	$ 30,983
Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	5,500	8,000	13,200	17,400
Asset and Property Management Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	7,551	11,110	16,876	22,641
Asset and Property Management Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	4,800	5,800	9,700	11,600
Leasing Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	682	1,381	3,678	2,880
Leasing Commissions [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	500	700	1,700	1,400
Disposition Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	210	1,515	1,766	2,717
Disposition Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	200	1,500	1,800	2,600
Credit Facility Guaranty and Refinancing Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	0	0	0	1,800
Credit Facility Guaranty and Refinancing Fees [Member] | Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with RVI	$ 0	$ 0	$ 0	$ 1,800