Fair Values - Schedule of Details of Book Value, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Financial assets
Cash and cash equivalents, book value	$ 322,104	$ 350,014
Cash and cash equivalents, fair value	322,104	350,014
Loans receivable, net, book value	20,591,458	23,210,076
Loan receivable, net, face amount	21,761,684	23,923,719
Loan receivable, net, fair value	20,480,151	23,015,737
Financial liabilities
Long-term debt, face amount	14,931,693
Loan participations sold, net, book value	103,489	337,179
Loan participations sold, net, face amount	103,500	337,721
Loan participations sold, net, fair value	103,114	333,745
Secured debt, net
Financial liabilities
Long-term debt	11,001,491	12,683,095
Long-term debt, face amount	11,012,558	12,697,058
Long-term debt, fair value	10,850,530	12,425,609
Securitized debt obligations, net
Financial liabilities
Long-term debt	2,248,307	2,505,417
Long-term debt, face amount	2,248,432	2,507,514
Long-term debt, fair value	2,078,131	2,323,441
Asset-specific debt, net
Financial liabilities
Long-term debt	1,197,056	1,000,210
Long-term debt, face amount	1,201,237	1,004,097
Long-term debt, fair value	1,189,085	992,357
Secured term loans, net
Financial liabilities
Long-term debt	2,089,715	2,101,632
Long-term debt, face amount	2,116,425	2,135,221
Long-term debt, fair value	2,080,160	2,102,950
Senior secured notes, net
Financial liabilities
Long-term debt	333,023	362,763
Long-term debt, face amount	335,316	366,090
Long-term debt, fair value	311,531	327,081
Convertible notes, net
Financial liabilities
Long-term debt	263,334	295,847
Long-term debt, face amount	266,157	300,000
Long-term debt, fair value	$ 254,845	$ 272,076