Loans - Allowance for Loan Losses, Allowance for Loan Losses and Recorded Investment by Portfolio Segment Based on Impairment Method (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	$ 12,794	$ 8,552
Purchased-credit impaired	50
Total allowance for loan losses	12,844	8,552	$ 7,869
Loans [Abstract]
Individually evaluated for impairment	14,522	8,673
Collectively evaluated for impairment	1,607,778	1,228,211
Purchased-credit impaired	1,231	10,241
Total loans	1,623,531	1,247,125
Residential Real Estate
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	3,951	4,155
Total allowance for loan losses	3,951	4,155	5,103
Loans [Abstract]
Individually evaluated for impairment	5,392	7,198
Collectively evaluated for impairment	510,866	436,942
Purchased-credit impaired		0
Total loans	516,258	444,140
Multi-family
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	4,308	2,433
Total allowance for loan losses	4,308	2,433	1,506
Loans [Abstract]
Individually evaluated for impairment	2,348	458
Collectively evaluated for impairment	572,713	266,256
Purchased-credit impaired		0
Total loans	575,061	266,714
Commercial Real Estate
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	3,707	1,884
Total allowance for loan losses	3,707	1,884	1,221
Loans [Abstract]
Individually evaluated for impairment	5,875	517
Collectively evaluated for impairment	466,507	339,966
Purchased-credit impaired	602	8,324
Total loans	472,984	348,807
Commercial and Industrial
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	711	79
Purchased-credit impaired	50
Total allowance for loan losses	761	79	38
Loans [Abstract]
Individually evaluated for impairment	907	500
Collectively evaluated for impairment	44,749	169,660
Purchased-credit impaired	629	1,917
Total loans	46,285	172,077
Construction and land development
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	115
Total allowance for loan losses	115
Loans [Abstract]
Collectively evaluated for impairment	12,907	15,374
Purchased-credit impaired		0
Total loans	12,907	15,374
Consumer
Allowance for Loan Losses [Abstract]
Collectively evaluated for impairment	2	1
Total allowance for loan losses	2	1	$ 1
Loans [Abstract]
Collectively evaluated for impairment	36	13
Purchased-credit impaired		0
Total loans	$ 36	$ 13

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Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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- Definition

The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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- Definition

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

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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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- Definition

Amortized cost, before allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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