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, 2026	Sep. 30, 2025
Financing Receivable, Modifications [Line Items]
Total	$ 127,844	$ 84,270
30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	15,226	758
90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	18,000	0
Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	61,318	65,355
Current
Financing Receivable, Modifications [Line Items]
Total	33,300	18,157
Commercial
Financing Receivable, Modifications [Line Items]
Total	111,549	66,764
Commercial \| 30-89 Days Past Due
Financing Receivable, Modifications [Line Items]
Total	15,226	758
Commercial \| 90+ Days Past Due
Financing Receivable, Modifications [Line Items]
Total	18,000	0
Commercial \| Non-Accrual
Financing Receivable, Modifications [Line Items]
Total	45,023	47,849
Commercial \| Current
Financing Receivable, Modifications [Line Items]
Total	33,300	18,157
Commercial real estate
Financing Receivable, Modifications [Line Items]
Total	16,295	17,506
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	16,295	17,506
Commercial real estate \| Current
Financing Receivable, Modifications [Line Items]
Total	$ 0	$ 0