LOANS AND LEASES, NET - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Sep. 30, 2025
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	$ 119,868		$ 119,868		$ 67,447
Average recorded investment	144,294	$ 50,173	109,828	$ 38,641
National Lending \| Term lending
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	70,295		70,295		33,042
Average recorded investment	92,218	30,308	60,055	27,012
National Lending \| Asset-based lending
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	24,169		24,169		24,273
Average recorded investment	20,332	6,996	22,779	2,970
National Lending \| Factoring
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	17,663		17,663		0
Average recorded investment	7,803	1,350	3,541	1,004
National Lending \| Lease financing
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	3,467		3,467		3,985
Average recorded investment	3,947	4,514	4,075	3,655
National Lending \| SBA/USDA
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	3,860		3,860		6,147
Average recorded investment	19,581	7,005	18,908	4,000
National Lending \| Other commercial finance
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	414		414		0
Average recorded investment	413	0	470	0
National Lending \| Commercial finance
Financing Receivable, Impaired [Line Items]
Impaired loans, unpaid balance	119,868		119,868		$ 67,447
Average recorded investment	$ 144,294	$ 50,173	$ 109,828	$ 38,641