INVESTMENTS IN LOANS AND SECURITIES - Schedule of Investments in Loans and Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 1,256,711		$ 811,874
Gross Unrealized Gains	13,828		19,313
Gross Unrealized Losses	(94,223)		(13,436)
Allowance for Credit Losses	(252,934)	$ (178,130)	(100,958)	$ (77,004)	$ (77,448)	$ 0
Fair Value	923,382		716,793
Accrued interest receivable	$ 13,400		$ 12,500
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Fees and other receivables (including related party receivables of $55,591 and $51,036 as of September 30, 2024 and December 31, 2023, respectively)		Fees and other receivables (including related party receivables of $55,591 and $51,036 as of September 30, 2024 and December 31, 2023, respectively)
Securitization notes
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 278,376		$ 91,654
Gross Unrealized Gains	514		629
Gross Unrealized Losses	(675)		(1,858)
Allowance for Credit Losses	0	0	0	0	0	0
Fair Value	278,215		90,425
Securitization certificates
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	971,470		715,646
Gross Unrealized Gains	13,314		18,684
Gross Unrealized Losses	(93,548)		(11,578)
Allowance for Credit Losses	(251,125)	(174,077)	(98,679)	(74,466)	(74,288)	0
Fair Value	640,111		624,073
Other loans and receivables
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	6,865		4,574
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Allowance for Credit Losses	(1,809)	$ (4,053)	(2,279)	$ (2,538)	$ (3,160)	$ 0
Fair Value	$ 5,056		$ 2,295