SHORT-TERM AND LONG-TERM BORROWINGS - Short Term Debt (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023
Short-Term Debt [Abstract]
Short-term borrowings	$ 377,000,000	$ 13,000,000
Total loans and leases, net	4,029,859,000	4,316,411,000
Securities sold under agreements to repurchase, total	0	0
Asset Pledged as Collateral
Short-Term Debt [Abstract]
Total loans and leases, net	136,900,000	21,300,000
Estimated Fair Value
Short-Term Debt [Abstract]
Fair value	4,036,490,000	4,223,010,000
Estimated Fair Value | Asset Pledged as Collateral with Right | Federal Home Loan Bank Advances
Short-Term Debt [Abstract]
Fair value	1,040,000,000.00	996,900,000
Overnight fed funds purchased
Short-Term Debt [Abstract]
Short-term borrowings	377,000,000	$ 13,000,000
Overnight fed funds purchased | FHLB
Short-Term Debt [Abstract]
Short-term borrowings	257,000,000
Overnight fed funds purchased | Other Financial Institutions
Short-Term Debt [Abstract]
Short-term borrowings	$ 120,000,000