Valuation and Qualifying Accounts and Reserves (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Standards Update 2016-02
Valuation and Qualifying Accounts Disclosure [Line Items]
Reserve of preferred equity interests and accrued interest		$ 105,300	$ 84,600
Allowance for uncollectible accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions of allowance	$ 127,913	$ 552
Allowance for uncollectible accounts [Member] | Spin-off [Member] | Retail Value Inc. [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions of allowance			13,500
Valuation allowance for deferred and prepaid tax assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions of allowance			22,807
Valuation allowance for deferred and prepaid tax assets [Member] | Accounting Standards Update 2016-02
Valuation and Qualifying Accounts Disclosure [Line Items]
Deductions of allowance			$ 14,800