Loans - Carrying Amount for Purchased Credit Impaired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Carrying Amount for Purchased Credit Impaired Loans [Abstract]
Total recorded investment	$ 1,231	$ 10,241
Allowance for loan losses	12,844	8,552	$ 7,869
Purchase Credit Impaired Loans
Carrying Amount for Purchased Credit Impaired Loans [Abstract]
Allowance for loan losses	50	0
Commercial Real Estate
Carrying Amount for Purchased Credit Impaired Loans [Abstract]
Total recorded investment	602	8,324
Allowance for loan losses	3,707	1,884	1,221
Commercial and Industrial
Carrying Amount for Purchased Credit Impaired Loans [Abstract]
Total recorded investment	629	1,917
Allowance for loan losses	$ 761	$ 79	$ 38

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant