Investment Securities (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Schedule of Available For Sale Securities [Line Items]
Investment securities, available for sale	$ 525,212	$ 526,251
Accrued interest receivable	60,434	59,398
Securities Investment
Schedule of Available For Sale Securities [Line Items]
Accrued interest receivable	1,959	2,399
U.S. government and agency obligations
Schedule of Available For Sale Securities [Line Items]
Investment securities, available for sale	54,003	72,776
U.S. government and agency obligations \| Asset Pledged as Collateral \| Margin requirement
Schedule of Available For Sale Securities [Line Items]
Investment securities, available for sale	$ 50,111	$ 68,932

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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+ Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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