Fair Values - Schedule of Details of Book Value, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financial assets
Cash and cash equivalents	$ 283,580	$ 551,154
Loans receivable, net	25,001,207	22,156,437
Debt securities held-to-maturity, net	0	79,200
Financial liabilities
Securitized debt obligations, net	2,841,901	2,838,062
Securitized debt obligations, net, Face Amount	2,855,625	2,855,625
Asset-specific debt net, Face Amount	870,684	400,699
Loan participations sold, net	225,884	0
Loan participations sold, net, Face Amount	226,511	0
Secured debt, net
Financial liabilities
Face Value	13,932,436	12,299,580
Secured term loans, net
Financial liabilities
Face Value	1,842,401	1,349,271
Senior secured notes, net
Financial liabilities
Face Value	400,000	400,000
Convertible notes, net
Financial liabilities
Face Value	520,000	622,500
Book Value
Financial assets
Cash and cash equivalents	283,580	551,154
Loans receivable, net	24,698,522	21,878,338
Debt securities held-to-maturity, net	0	78,013
Financial liabilities
Securitized debt obligations, net	2,841,901	2,838,062
Asset-specific debt, net	860,007	393,824
Loan participations sold, net	225,884	0
Book Value | Secured debt, net
Financial liabilities
Debt	13,905,949	12,280,042
Book Value | Secured term loans, net
Financial liabilities
Debt	1,809,942	1,327,406
Book Value | Senior secured notes, net
Financial liabilities
Debt	394,562	394,010
Book Value | Convertible notes, net
Financial liabilities
Debt	512,994	619,876
Fair Value
Financial assets
Cash and cash equivalents	283,580	551,154
Loans receivable, net	24,609,487	22,013,762
Debt securities held-to-maturity, net	0	77,229
Financial liabilities
Securitized debt obligations, net	2,783,170	2,850,399
Asset-specific debt, net	863,919	400,699
Loan participations sold, net	226,511	0
Fair Value | Secured debt, net
Financial liabilities
Debt	13,679,307	12,299,580
Fair Value | Secured term loans, net
Financial liabilities
Debt	1,745,307	1,335,844
Fair Value | Senior secured notes, net
Financial liabilities
Debt	349,212	399,012
Fair Value | Convertible notes, net
Financial liabilities
Debt	$ 490,006	$ 630,821