Loans Receivable, Net and Allowance for Credit Losses on Loans - Schedule of Loans Evaluated for Impairment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,720,158	$ 1,699,050
Individually Evaluated for Impairment	9,830	9,735
Collectively Evaluated for Impairment	1,710,328	1,689,315
Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	40,427	48,143
Individually Evaluated for Impairment	635	648
Collectively Evaluated for Impairment	39,792	47,495
Real Estate Loans [Member] \| Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	712,035	713,326
Individually Evaluated for Impairment	1,624	1,393
Collectively Evaluated for Impairment	710,411	711,933
Real Estate Loans [Member] \| Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	15,859	16,768
Collectively Evaluated for Impairment	15,859	16,768
Real Estate Loans [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	851,098	821,958
Individually Evaluated for Impairment	7,540	7,664
Collectively Evaluated for Impairment	843,558	814,294
Obligations of States and Political Subdivisions [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	49,487	48,118
Collectively Evaluated for Impairment	49,487	48,118
Home Equity Loans and Lines of Credit [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	49,323	48,212
Individually Evaluated for Impairment	25	27
Collectively Evaluated for Impairment	49,298	48,185
Auto Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	292	523
Individually Evaluated for Impairment	4
Collectively Evaluated for Impairment	288	523
Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,637	2,002
Individually Evaluated for Impairment	2	3
Collectively Evaluated for Impairment	$ 1,635	$ 1,999

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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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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