Variable Interest Entities - Assets and Liabilities of Consolidated VIEs (Detail) - USD ($)	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Assets
Cash and cash equivalents	$ 322,104,000			$ 350,014,000
Loans receivable	21,602,517,000			23,787,012,000
Current expected credit loss reserve	(1,011,059,000)	$ (893,938,000)	$ (751,370,000)	(576,936,000)	$ (463,423,000)	$ (363,875,000)	$ (336,591,000)	$ (326,137,000)
Loans receivable, net	20,591,458,000			23,210,076,000
Real estate owned, net	138,725,000			0
Other assets	390,907,000			476,088,000
Total Assets	21,443,194,000			24,036,178,000
Liabilities
Other liabilities	346,382,000			362,531,000
Total Liabilities	17,582,797,000			19,648,674,000
Securitized debt obligations, net
Liabilities
Securitized debt obligations, net	2,248,307,000			2,505,417,000
VIE
Assets
Cash and cash equivalents	2,014,000			0
Loans receivable	2,892,807,000			3,061,278,000
Current expected credit loss reserve	(261,536,000)			(183,508,000)
Loans receivable, net	2,631,271,000			2,877,770,000
Real estate owned, net	46,638,000			0
Other assets	28,583,000			103,692,000
Total Assets	2,708,506,000			2,981,462,000
Liabilities
Other liabilities	5,774,000			8,101,000
Total Liabilities	2,254,081,000			2,513,518,000
VIE | Securitized debt obligations, net
Liabilities
Securitized debt obligations, net	$ 2,248,307,000			$ 2,505,417,000