Loans and Allowance for Credit Losses on Loans - Schedule of Age Analysis of Gross Modified Loans Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Modifications [Line Items]
Total	$ 30,496	$ 58,617
30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	10,191	5,893
Current
Financing Receivable, Modifications [Line Items]
Total	20,305	52,724
Commercial
Financing Receivable, Modifications [Line Items]
Total	14,665	58,617
Commercial \| 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Commercial \| 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Commercial \| Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	10,191	5,893
Commercial \| Current
Financing Receivable, Modifications [Line Items]
Total	4,474	$ 52,724
Commercial real estate
Financing Receivable, Modifications [Line Items]
Total	15,831
Commercial real estate \| 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0
Commercial real estate \| 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0
Commercial real estate \| Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	0
Commercial real estate \| Current
Financing Receivable, Modifications [Line Items]
Total	$ 15,831