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Loans and ACL - Summary of Loan Modifications by Past Due Status (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	$ 9,056	$ 8,202
Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	9,056	8,202
30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Secured
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	4,114	1,937
Secured | Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	4,114	1,937
Secured | 30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Secured | 60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Secured | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Commercial mortgage owner occupied
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	2,832	823
Commercial mortgage owner occupied | Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	2,832	823
Commercial mortgage owner occupied | 30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Commercial mortgage owner occupied | 60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Commercial mortgage owner occupied | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Commercial mortgage multifamily
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		2,917
Commercial mortgage multifamily | Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		2,917
Commercial mortgage multifamily | 30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		0
Commercial mortgage multifamily | 60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		0
Commercial mortgage multifamily | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		0
Agricultural mortgage
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	1,185	1,305
Agricultural mortgage | Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	1,185	1,305
Agricultural mortgage | 30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Agricultural mortgage | 60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Agricultural mortgage | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Agricultural other
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	925	1,219
Agricultural other | Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	925	1,219
Agricultural other | 30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Agricultural other | 60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	0	0
Agricultural other | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months	$ 0	0
Secured - indirect
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		1
Secured - indirect | Current
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		1
Secured - indirect | 30-59 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		0
Secured - indirect | 60-89 Days Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		0
Secured - indirect | 90 Days or More Past Due
Financing Receivable, Modified [Line Items]
Financing receivable modified after 12 months		$ 0

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Amortized cost excluding accrued interest, of financing receivable 12 months after modification for debtor experiencing financial difficulty.

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