LOANS AND LEASES - Schedule of Loan Modifications, Aging Analysis (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Current
Financing Receivable, Modified [Line Items]
Total	$ 32.2	$ 20.5
30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	1.8	3.2
90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	4.1	0.6
Total commercial loans and leases | Current
Financing Receivable, Modified [Line Items]
Total	23.8	14.1
Total commercial loans and leases | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.8	0.0
Total commercial loans and leases | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	3.1	0.0
Total commercial loans and leases | Commercial real estate | Current
Financing Receivable, Modified [Line Items]
Total	20.9	13.5
Total commercial loans and leases | Commercial real estate | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.0	0.0
Total commercial loans and leases | Commercial real estate | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	1.3	0.0
Total commercial loans and leases | Commercial and industrial | Current
Financing Receivable, Modified [Line Items]
Total	2.9	0.6
Total commercial loans and leases | Commercial and industrial | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.8	0.0
Total commercial loans and leases | Commercial and industrial | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	1.8	0.0
Total consumer loans | Current
Financing Receivable, Modified [Line Items]
Total	8.4	6.4
Total consumer loans | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	1.0	3.2
Total consumer loans | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	1.0	0.6
Total consumer loans | Direct installment | Current
Financing Receivable, Modified [Line Items]
Total	1.8	1.6
Total consumer loans | Direct installment | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.0	0.2
Total consumer loans | Direct installment | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.3	0.0
Total consumer loans | Residential mortgages | Current
Financing Receivable, Modified [Line Items]
Total	5.6	3.3
Total consumer loans | Residential mortgages | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	1.0	2.7
Total consumer loans | Residential mortgages | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.7	0.6
Total consumer loans | Consumer lines of credit | Current
Financing Receivable, Modified [Line Items]
Total	1.0	1.5
Total consumer loans | Consumer lines of credit | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Total	0.0	0.3
Total consumer loans | Consumer lines of credit | 90+ Days Past Due
Financing Receivable, Modified [Line Items]
Total	$ 0.0	$ 0.0