Other Assets and Liabilities - Summary of Components of Other Assets (Parenthetical) (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Schedule Of Other Assets [Line Items]
Percentage of yield in subordinate risk retention interest	10.00%
Restricted cash	$ 25,000	$ 0	$ 0
2021 FL4 CLO [Member]
Schedule Of Other Assets [Line Items]
Restricted cash	25,000
2018 Single Asset Securitization [Member]
Schedule Of Other Assets [Line Items]
Single asset securitization principal amount	$ 493,300	$ 735,500
Single asset securitization maximum maturity date	Jun. 09, 2025