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Disclosures About Fair Value of Assets - Quantitative Information about Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements (Detail)	3 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) yr mo	Jun. 30, 2023 USD ($) yr mo
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights	$ 1,540,000	$ 1,482,000
State and political subdivision	$ 2,361,000	$ 2,361,000
Discount rate [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	9.5	9.5
Minimum [Member] | Constant prepayment rate [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	6.1	6
Minimum [Member] | Probability of Default [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	0.1	0.09
Minimum [Member] | Maturity/Call Date [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input | mo	1	1
Minimum [Member] | Weighted average coupon [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	2.97	2.97
Minimum [Member] | Marketability yield adjustment [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	1	1
Maximum [Member] | Constant prepayment rate [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	6.9	7
Maximum [Member] | Probability of Default [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	0.14	0.12
Maximum [Member] | Maturity/Call Date [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input | yr	9	9
Maximum [Member] | Weighted average coupon [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	3.08	3.08
Maximum [Member] | Marketability yield adjustment [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	2	2
Weighted Average [Member] | Discount rate [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	9.5	9.5
Weighted Average [Member] | Constant prepayment rate [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	6.6	6.9
Weighted Average [Member] | Probability of Default [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	0.12	0.12
Weighted Average [Member] | Weighted average coupon [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	3.03	3.03
Weighted Average [Member] | Marketability yield adjustment [Member] | Discounted Cash Flow [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Mortgage servicing rights, measurement input	1.6	1.6

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