SHORT-TERM AND LONG-TERM BORROWINGS - Short Term Debt (Details) - USD ($)	Sep. 30, 2022	Sep. 30, 2021
Debt Instrument [Line Items]
Loans	$ 3,490,358,000	$ 3,541,282,000
Securities sold under agreements to repurchase, total	0
Estimated Fair Value
Debt Instrument [Line Items]
Loans and leases	3,525,803,000	3,616,646,000
Asset Pledged as Collateral
Debt Instrument [Line Items]
Loans	0	0
Asset Pledged as Collateral with Right \| Estimated Fair Value \| Short-term FHLB advances
Debt Instrument [Line Items]
Loans and leases	804,000,000	644,700,000
Asset Pledged as Collateral with Right \| Estimated Fair Value \| Repurchase agreements
Debt Instrument [Line Items]
Loans and leases	$ 0	$ 0

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Amortized cost excluding accrued interest, after allowance for credit loss, of financing receivable. Excludes net investment in lease.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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