Loans and Allowance for Credit Losses - Additional Information (Detail)	3 Months Ended	12 Months Ended
Sep. 30, 2023 USD ($) SecurityLoan	Jun. 30, 2023 USD ($) SecurityLoan
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
Foreclosed residential real estate properties	$ 31,000	$ 31,000
Fair Value, Concentration of Risk, Collateral Policy [Member]
Loans and Allowance for Credit Losses [Line Items]
Commercial and multi-family real estate	$ 343,987,000	328,721,000
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	$ 24,000
One- to four-family [Member]
Loans and Allowance for Credit Losses [Line Items]
Loans held for sale	$ 51,000	0
Maximum term of fixed-rate one- to four-family residential mortgage loans	15 years
Purchased Loans and Loan Participations [Member]
Loans and Allowance for Credit Losses [Line Items]
Approximate amount of purchase loans included in loans receivable	$ 629,000	652,000
Approximate amount of loans included on out-of-area participation	46,861,000	46,073,000
Amount within 100 miles of primary area	$ 29,821,000	$ 28,951,000

Loans and Allowance for Credit Losses [Line Items]

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- Definition

Loans and leases receivable commercial loan participations.

+ References

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- Definition

Loans and leases receivable loans commercial loan participations outside primary market area.

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- Definition

Loans and leases receivable purchased loans.

+ References

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- Definition

Minimum period for default.

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- Definition

Term period on residential mortgage loan.

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- Definition

This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Publisher FASB
-URI https://asc.fasb.org//310-10/tableOfContent

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- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-34

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- Definition

Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481852/948-310-45-1

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-11

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