Loans - Aging Analysis of Loan Modifications (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Modified [Line Items]
Accumulated modifications	$ 14,777	$ 14,555
Current
Financing Receivable, Modified [Line Items]
Accumulated modifications	888	14,319
30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	479	65
90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	0	0
Total Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	13,410	171
Commercial mortgage
Financing Receivable, Modified [Line Items]
Accumulated modifications	681	236
Commercial mortgage | Current
Financing Receivable, Modified [Line Items]
Accumulated modifications	0	0
Commercial mortgage | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	0	65
Commercial mortgage | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	0	0
Commercial mortgage | Total Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	681	171
Commercial and industrial
Financing Receivable, Modified [Line Items]
Accumulated modifications	14,096	14,319
Commercial and industrial | Current
Financing Receivable, Modified [Line Items]
Accumulated modifications	888	14,319
Commercial and industrial | 30-89 Days Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	479	0
Commercial and industrial | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	0	0
Commercial and industrial | Total Past Due
Financing Receivable, Modified [Line Items]
Accumulated modifications	$ 12,729	$ 0