Fair Values - Schedule of Details of Book Value, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets
Cash and cash equivalents	$ 350,014	$ 291,340
Loans receivable, net	23,923,719	25,160,343
Financial liabilities
Securitized debt obligations, net	2,505,417	2,664,010
Securitized debt obligations, net, Face Amount	2,507,514	2,673,541
Asset-specific debt net, Face Amount	1,004,097	950,278
Loan participations sold, net	337,179	224,232
Loan participations sold, net, Face Amount	337,721	224,744
Secured debt, net
Financial liabilities
Debt, Face Amount	12,697,058	13,549,748
Secured term loans, net
Financial liabilities
Debt, Face Amount	2,135,221	2,157,218
Senior secured notes, net
Financial liabilities
Debt, Face Amount	366,090	400,000
Convertible notes, net
Financial liabilities
Debt, Face Amount	300,000	520,000
Book Value
Financial assets
Cash and cash equivalents	350,014	291,340
Loans receivable, net	23,210,076	24,691,743
Financial liabilities
Securitized debt obligations, net	2,505,417	2,664,010
Asset-specific debt, net	1,000,210	942,503
Loan participations sold, net	337,179	224,232
Book Value | Secured debt, net
Financial liabilities
Debt	12,683,095	13,528,164
Book Value | Secured term loans, net
Financial liabilities
Debt	2,101,632	2,114,549
Book Value | Senior secured notes, net
Financial liabilities
Debt	362,763	395,166
Book Value | Convertible notes, net
Financial liabilities
Debt	295,847	514,257
Fair Value
Financial assets
Cash and cash equivalents	350,014	291,340
Loans receivable, net	23,015,737	24,445,042
Financial liabilities
Securitized debt obligations, net	2,323,441	2,597,377
Asset-specific debt, net	992,357	934,815
Loan participations sold, net	333,745	217,717
Fair Value | Secured debt, net
Financial liabilities
Debt	12,425,609	13,121,306
Fair Value | Secured term loans, net
Financial liabilities
Debt	2,102,950	2,103,943
Fair Value | Senior secured notes, net
Financial liabilities
Debt	327,081	343,665
Fair Value | Convertible notes, net
Financial liabilities
Debt	$ 272,076	$ 478,232