Securitized Debt Obligations, Net - Schedule of Information on Securitized Debt Obligations (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) loan	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) loan
Debt Instrument [Line Items]
Credit spread adjustment (percentage)	0.11%		0.11%
Interest expense on securitized debt obligations	$ 11,000	$ 12,100
Financing provided
Debt Instrument [Line Items]
Count | loan	3		3
Principal Balance	$ 2,855,625		$ 2,855,625
Book Value	$ 2,839,818		$ 2,838,062
Financing provided | 2021 FL4 Collateralized Loan Obligation
Debt Instrument [Line Items]
Count | loan	1		1
Principal Balance	$ 803,750		$ 803,750
Book Value	$ 797,870		$ 797,373
Financing provided | 2020 FL3 Collateralized Loan Obligation
Debt Instrument [Line Items]
Count | loan	1		1
Principal Balance	$ 808,750		$ 808,750
Book Value	$ 804,658		$ 804,096
Financing provided | 2020 FL2 Collateralized Loan Obligation
Debt Instrument [Line Items]
Count | loan	1		1
Principal Balance	$ 1,243,125		$ 1,243,125
Book Value	$ 1,237,290		$ 1,236,593
Collateral assets
Debt Instrument [Line Items]
Count | loan	67		73
Principal Balance	$ 3,500,000		$ 3,500,000
Book Value	$ 3,500,000		$ 3,500,000
Collateral assets | 2021 FL4 Collateralized Loan Obligation
Debt Instrument [Line Items]
Count | loan	33		34
Principal Balance	$ 1,000,000		$ 1,000,000
Book Value	$ 1,000,000		$ 1,000,000
Collateral assets | 2020 FL3 Collateralized Loan Obligation
Debt Instrument [Line Items]
Count | loan	16		18
Principal Balance	$ 1,000,000		$ 1,000,000
Book Value	$ 1,000,000		$ 1,000,000
Collateral assets | 2020 FL2 Collateralized Loan Obligation
Debt Instrument [Line Items]
Count | loan	18		21
Principal Balance	$ 1,500,000		$ 1,500,000
Book Value	$ 1,500,000		$ 1,500,000
LIBOR
Debt Instrument [Line Items]
One-month USD LIBOR	0.45%		0.10%
LIBOR | Financing provided
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	1.62%		1.69%
LIBOR | Financing provided | 2021 FL4 Collateralized Loan Obligation
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	1.56%		1.66%
LIBOR | Financing provided | 2020 FL3 Collateralized Loan Obligation
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	2.03%		2.10%
LIBOR | Financing provided | 2020 FL2 Collateralized Loan Obligation
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	1.39%		1.45%
LIBOR | Collateral assets
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	3.33%		3.20%
LIBOR | Collateral assets | 2021 FL4 Collateralized Loan Obligation
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	3.54%		3.42%
LIBOR | Collateral assets | 2020 FL3 Collateralized Loan Obligation
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	3.18%		3.06%
LIBOR | Collateral assets | 2020 FL2 Collateralized Loan Obligation
Debt Instrument [Line Items]
Wtd. Avg. Yield/Cost	3.29%		3.15%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
30 day average compounded SOFR reference rate	0.30%		0.05%