Investment in and Advances to Affiliate - Schedule of Revenue From Contracts With Customers Included in Fee and Other Income on Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	$ 11,945	$ 14,394	$ 42,928	$ 28,437
Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	6,100	8,900	23,500	8,900
Asset and Property Management Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	9,751	10,501	32,392	20,982
Asset and Property Management Fees [Member] \| Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	5,100	6,500	16,600	6,500
Leasing Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	1,036	1,818	3,916	4,752
Leasing Commissions [Member] \| Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	400	700	1,800	700
Disposition Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	546	1,622	3,263	1,622
Disposition Fees [Member] \| Retail Value Inc. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	500	1,600	3,200	1,600
Credit Facility Guaranty and Refinancing Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from contracts with customers	60	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 customers	$ 100	$ 100	$ 1,900	$ 100