Fair Values - Schedule of Details of Book Value, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financial assets
Cash and cash equivalents	$ 515,808	$ 291,340
Loans receivable, net	25,020,489	25,160,343
Financial liabilities
Securitized debt obligations, net	2,664,208	2,664,010
Securitized debt obligations, net, Face Amount	2,671,734	2,673,541
Asset-specific debt net, Face Amount	822,873	950,278
Loan participations sold, net	229,003	224,232
Loan participations sold, net, Face Amount	229,468	224,744
Secured debt, net
Financial liabilities
Debt, Face Amount	14,051,435	13,549,748
Secured term loans, net
Financial liabilities
Debt, Face Amount	2,151,719	2,157,218
Senior secured notes, net
Financial liabilities
Debt, Face Amount	400,000	400,000
Convertible notes, net
Financial liabilities
Debt, Face Amount	300,000	520,000
Book Value
Financial assets
Cash and cash equivalents	515,808	291,340
Loans receivable, net	24,559,773	24,691,743
Financial liabilities
Securitized debt obligations, net	2,664,208	2,664,010
Asset-specific debt, net	817,444	942,503
Loan participations sold, net	229,003	224,232
Book Value | Secured debt, net
Financial liabilities
Debt	14,029,486	13,528,164
Book Value | Secured term loans, net
Financial liabilities
Debt	2,111,232	2,114,549
Book Value | Senior secured notes, net
Financial liabilities
Debt	395,461	395,166
Book Value | Convertible notes, net
Financial liabilities
Debt	294,888	514,257
Fair Value
Financial assets
Cash and cash equivalents	515,808	291,340
Loans receivable, net	24,314,435	24,445,042
Financial liabilities
Securitized debt obligations, net	2,557,118	2,597,377
Asset-specific debt, net	815,049	934,815
Loan participations sold, net	222,681	217,717
Fair Value | Secured debt, net
Financial liabilities
Debt	13,640,859	13,121,306
Fair Value | Secured term loans, net
Financial liabilities
Debt	1,974,538	2,103,943
Fair Value | Senior secured notes, net
Financial liabilities
Debt	315,944	343,665
Fair Value | Convertible notes, net
Financial liabilities
Debt	$ 240,711	$ 478,232