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BORROWINGS - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024
Federal Home Loan Bank, Advance, Branch of FHLBank [Line Items] |  |
Borrowings | $ 1,765,604 | $ 3,267,589
Weighted average effective maturity of FHLB advances | 2 years 2 months 8 days |
FRB Bank Term Funding Program |  |
Federal Home Loan Bank, Advance, Branch of FHLBank [Line Items] |  |
Borrowings |  | $ 1,074,714
Federal Home Loan Bank of Des Moines |  |
Federal Home Loan Bank, Advance, Branch of FHLBank [Line Items] |  |
Federal home loan bank, percent of assets | 45.00% |

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