Loans and Allowance for Credit Losses - Allowance for off-balance credit exposure (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	$ 1,959
Provision (benefit) charged to expense	(422)	$ 648	$ 149
Balance, end of period	1,805	1,959
Impact of ASU 2016-13 adoption
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	268
Balance, end of period		268
Residential Real Estate
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	19
Provision (benefit) charged to expense	(17)
Balance, end of period	37	19
Residential Real Estate | Impact of ASU 2016-13 adoption
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	35
Balance, end of period		35
Construction Real Estate
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	769
Provision (benefit) charged to expense	(100)
Balance, end of period	502	769
Construction Real Estate | Impact of ASU 2016-13 adoption
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	(167)
Balance, end of period		(167)
Commercial Real Estate
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	172
Provision (benefit) charged to expense	(79)
Balance, end of period	188	172
Commercial Real Estate | Impact of ASU 2016-13 adoption
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	95
Balance, end of period		95
Consumer loans
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	153
Provision (benefit) charged to expense	(132)
Balance, end of period	218	153
Consumer loans | Impact of ASU 2016-13 adoption
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	197
Balance, end of period		197
Commercial loans
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	846
Provision (benefit) charged to expense	(94)
Balance, end of period	860	846
Commercial loans | Impact of ASU 2016-13 adoption
Allowance for off-balance sheet credit exposure:
Balance, beginning of period	$ 108
Balance, end of period		$ 108