Securitized Debt Obligations, Net - Schedule of Information on Securitized Debt Obligations (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Percentage of loans financed by securitized debt obligations earned floating rate of interest		98.00%
Interest expense on securitized debt obligations	$ 47.2	$ 48.8
USD LIBOR [Member]
Debt Instrument [Line Items]
Percentage of loans, fixed rate	1.00%
Collateral Assets [Member] | USD LIBOR [Member]
Debt Instrument [Line Items]
Percentage of loans, fixed rate	2.00%
Collateral Assets [Member] | Single Asset Securitization [Member]
Debt Instrument [Line Items]
Total loan amount, securitized	$ 500.0