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, 2025	Sep. 30, 2024
Financing Receivable, Modifications [Line Items]
Total	$ 84,270	$ 30,496
30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	758	0
90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	65,355	10,191
Current
Financing Receivable, Modifications [Line Items]
Total	18,157	20,305
Commercial
Financing Receivable, Modifications [Line Items]
Total	66,764	14,665
Commercial \| 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	758	0
Commercial \| 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Commercial \| Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	47,849	10,191
Commercial \| Current
Financing Receivable, Modifications [Line Items]
Total	18,157	4,474
Commercial real estate
Financing Receivable, Modifications [Line Items]
Total	17,506	15,831
Commercial real estate \| 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Commercial real estate \| 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	0	0
Commercial real estate \| Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	17,506	0
Commercial real estate \| Current
Financing Receivable, Modifications [Line Items]
Total	$ 0	$ 15,831