Fair Values - Schedule of Details of Book Value, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financial assets
Cash and cash equivalents	$ 551,154	$ 289,970
Loans receivable, net	22,156,437	16,652,824
Debt securities held-to-maturity, net	79,200	79,200
Financial liabilities
Securitized debt obligations, net	2,838,062	2,922,499
Securitized debt obligations, net, Face Amount	2,855,625	2,940,638
Asset-specific debt net, Face Amount	400,699	399,699
Secured debt, net
Financial liabilities
Face amount	12,299,580	7,896,863
Secured term loans, net
Financial liabilities
Face amount	1,349,271	1,062,766
Senior secured notes, net
Financial liabilities
Face amount	400,000	0
Convertible notes, net
Financial liabilities
Face amount	622,500	622,500
Book Value
Financial assets
Cash and cash equivalents	551,154	289,970
Loans receivable, net	21,878,338	16,399,166
Debt securities held-to-maturity, net	78,013	75,722
Financial liabilities
Securitized debt obligations, net	2,838,062	2,922,499
Asset-specific debt, net	393,824	391,269
Book Value | Secured debt, net
Financial liabilities
Debt	12,280,042	7,880,536
Book Value | Secured term loans, net
Financial liabilities
Debt	1,327,406	1,041,704
Book Value | Senior secured notes, net
Financial liabilities
Debt	394,010	0
Book Value | Convertible notes, net
Financial liabilities
Debt	619,876	616,389
Estimate of Fair Value Measurement
Financial assets
Cash and cash equivalents	551,154	289,970
Loans receivable, net	22,013,762	16,447,192
Debt securities held-to-maturity, net	77,229	70,127
Financial liabilities
Securitized debt obligations, net	2,850,399	2,923,489
Asset-specific debt, net	400,699	399,699
Estimate of Fair Value Measurement | Secured debt, net
Financial liabilities
Debt	12,299,580	7,896,863
Estimate of Fair Value Measurement | Secured term loans, net
Financial liabilities
Debt	1,335,844	1,053,060
Estimate of Fair Value Measurement | Senior secured notes, net
Financial liabilities
Debt	399,012	0
Estimate of Fair Value Measurement | Convertible notes, net
Financial liabilities
Debt	$ 630,821	$ 621,568