Loans and Allowance for Credit Losses - Classes of loans information (Details)			12 Months Ended
	Jan. 20, 2023 USD ($)	Feb. 25, 2022 USD ($)	Jun. 30, 2023 USD ($) loan	Jun. 30, 2022 USD ($) loan	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)
Allowance for credit losses			$ 14,131,000	$ (66,000)	$ (602,000)
Allowance for credit losses for purchased credit deteriorated (PCD)			17,100,000	1,500,000	1,000,000.0
Off-balance sheet credit exposures			6,288,000	$ 3,358,000	1,805,000	$ 1,959,000
Impact of acquisition on provision on credit losses (PCL)			10,100,000
Impact of acquisition on allowance for credit losses (ACL)			8,900,000
Impact of acquisition on off-balance sheet credit exposure			$ 1,200,000
Net charge offs on average loans outstanding (as percentage)			0.02%	0.01%
Citizens Bancshares Company
Allowance for credit losses			$ 5,200,000
Allowance for credit losses for purchased credit deteriorated (PCD)	$ 1,121,000		1,100,000
Off-balance sheet credit exposures			1,800,000
Fortune
Allowance for credit losses for purchased credit deteriorated (PCD)		$ 120,000		$ 120,000
ACL required for non-PCD loans acquired			1,900,000
Credit exposure			120,000
Negative PCL				533,000
Secured by properties located outside lending area
Loans Receivable			$ 618,600,000
Residential Real Estate.
Fixed-rate and adjustable-rate mortgage (ARM) loans amortization period (in years)			30 years
Residential Real Estate. | Single Family
Maximum percentage of appraised value or purchase price that loans cannot exceed			90.00%
Residential Real Estate. | Multifamily
Maximum percentage of appraised value or purchase price that loans cannot exceed			85.00%
Amortization period of loans			25 years
Amortization period of multi-family residential loans if balloon maturities			10 years
Commercial
Amortization period of loans			25 years
Term of fixed interest applicability on loans			10 years
Term of variable interest applicability on loans			7 years
Agricultural real estate terms if 80% loan-to-value ratio			25 years
Agricultural real estate terms if 75% loan-to-value ratio			30 years
Loans Receivable			$ 1,600,000,000
Residential Real Estate
Amortization period of loans			30 years
Allowance for credit losses			$ 6,655,000	(2,238,000)	2,973,000
Off-balance sheet credit exposures			$ 71,000	58,000	37,000	19,000
Residential Real Estate | Minimum
Maturities of single-family residential construction loans			6 months
Residential Real Estate | Maximum
Maturities of single-family residential construction loans			12 months
Commercial Real Estate
Amortization period of loans			25 years
Allowance for credit losses			$ 5,605,000	2,251,000	(1,364,000)
Off-balance sheet credit exposures			$ 475,000	421,000	188,000	172,000
Construction Real Estate
Average term of construction loans			12 months
Allowance for credit losses			$ 432,000	46,000	281,000
Off-balance sheet credit exposures			$ 4,809,000	2,178,000	502,000	769,000
Construction Real Estate | Minimum
Maturities of multifamily or commercial construction loans			12 months
Construction Real Estate | Maximum
Maturities of multifamily or commercial construction loans			36 months
Consumer loans
Amortization period of loans			66 months
Allowance for credit losses			$ 334,000	(205,000)	(1,232,000)
Off-balance sheet credit exposures			$ 73,000	61,000	218,000	153,000
Consumer loans | Home Equity Loan
Maximum percentage of appraised value or purchase price that loans cannot exceed			90.00%
Amortization period of loans			10 years
Consumer loans | Automobile loans
Maximum percentage of appraised value or purchase price that loans cannot exceed			100.00%
Amortization period of loans			66 months
Commercial loans
Amortization period of loans			5 years
Amortization period of multi-family residential loans if balloon maturities			1 year
Allowance for credit losses			$ 1,105,000	80,000	(1,260,000)
Off-balance sheet credit exposures			$ 860,000	$ 640,000	$ 860,000	$ 846,000
Modifications for the purpose of extending the maturity date | Construction Real Estate
Incremental period that the loan maturity can be extended to			3 months
Number of construction loans outstanding, for which a modification had been agreed to | loan			53	57
Construction loans outstanding, for which a modification had been agreed to			$ 33,400,000	$ 13,800,000