SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loans Held for Sale (Details) - National Lending - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Consumer
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance, Reconciliation to Cash Flow [Roll Forward]
Beginning of year balance	$ 77,779	$ 21,071
Originations	1,901,593	1,206,201
Proceeds from sales	(1,937,079)	(1,123,271)
Gain (loss) on sales	0	0
Principal collections, net of deferred fees and costs	18,083	26,222
Non-cash transfers, net	0	0
End of year balance	24,210	77,779
Commercial
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance, Reconciliation to Cash Flow [Roll Forward]
Beginning of year balance	0	0
Originations	133,388	2,483
Proceeds from sales	(99,005)	(16,610)
Gain (loss) on sales	5,102	268
Principal collections, net of deferred fees and costs	48	280
Non-cash transfers, net	563,495	13,579
End of year balance	$ 602,932	$ 0