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Loans and Allowance for Credit Losses - Additional Information (Detail) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2022 USD ($) Loans SecurityLoan | Jun. 30, 2022 USD ($) Loans SecurityLoan | Sep. 30, 2021 USD ($) Loans
Loans and Allowance for Credit Losses [Line Items] |  |  |
Maximum term of fixed-rate one- to four-family residential mortgage loans | 15 years |  |
Number of default loans | SecurityLoan | 0 | 0 |
Investment recorded prior to modification | $ 0 | $ 0 |
Residential real estate properties foreclosure proceedings | 739,000 |  |
Foreclosed residential real estate properties | 0 | 120,000 |
Loans and Leases Receivable, Gross | 550,905,000 | 525,736,000 | $ 512,984,000
Fair Value, Concentration of Risk, Collateral Policy [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Commercial and multi-family real estate | $ 310,300,000 | 290,972,000 |
Troubled Debt Restructurings [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Minimum period for default | 90 days |  |
Residential Real Estate [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Foreclosed residential real estate properties | $ 0 |  |
Commercial Business Loans [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Loans and Leases Receivable, Gross | $ 77,103,000 | $ 80,418,000 | $ 88,962,000
Commercial Business Loans [Member] | Small Business Administration Paycheck Protection Programme Loans [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Percentage of government guarantee for loans as per scheme | 100.00% |  |
Commercial Portfolio And Commercial Residential Portfolio [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Number of loans as on closing date | Loans | 0 | 0 | 165
Loans and Leases Receivable, Gross |  |  | $ 14,300,000
One- to four-family [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Loans held for sale | $ 0 | $ 227,000 |
Maximum term of fixed-rate one- to four-family residential mortgage loans | 15 years |  |
Loans and Leases Receivable, Gross | $ 142,417,000 | 132,474,000 | $ 117,854,000
Purchased Loans and Loan Participations [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Approximate amount of purchase loans included in loans receivable | 1,527,000 | 1,570,000 |
Approximate amount of loans included on out-of-area participation | 37,134,000 | 29,972,000 |
Amount within 100 miles of primary area | 20,501,000 | $ 13,234,000 |
Troubled Debt Restructurings [Member] | Covid Nineteen [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Investment recorded post modification | $ 46,700,000 |  |
Troubled Debt Restructurings [Member] | Modification one [Member] | Covid Nineteen [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Number of Modifications | Loans | 89 |  |
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 43,700,000 |  |
Troubled Debt Restructurings [Member] | Modification Two [Member] | Covid Nineteen [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Number of Modifications | Loans | 86 |  |
Financing Receivable, Modifications, Post-Modification Recorded Investment | $ 3,100,000 |  |
Non troubled debt restructuring [Member] | Covid Nineteen [Member] | Financing receivables, 30 to 59 days past due [Member] |  |  |
Loans and Allowance for Credit Losses [Line Items] |  |  |
Financing receivable number of days past due | 30 days |  |
Period of loan excecution | 60 days |  |

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