Loans - Activity in the allowance for credit losses by portfolio segment (Details) - USD ($)	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	$ 2,158,590
Provision for credit losses	2,025,197
Provision for Credit Losses-Loans	41,000
Ending Balance September 30, 2023	2,025,197
Consumer
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	2,000
Provision for credit losses	3,000
Provision for Credit Losses-Loans	(10,000)
Ending Balance September 30, 2023	3,000
Commercial real estate | Commercial real estate
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	1,196,479
Provision for credit losses	380,000
Provision for Credit Losses-Loans	2,000
Ending Balance September 30, 2023	380,000
Commercial | Commercial and industrial
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	17,711
Provision for credit losses	23,000
Ending Balance September 30, 2023	23,000
Commercial | Construction
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	6,302
Provision for credit losses	6,000
Provision for Credit Losses-Loans	(2,000)
Ending Balance September 30, 2023	6,000
Residential | One-to-four-family residential
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	206,771
Provision for credit losses	1,388,000
Provision for Credit Losses-Loans	44,000
Ending Balance September 30, 2023	1,388,000
Residential | Multi-family real estate
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	365,401
Provision for credit losses	225,000
Provision for Credit Losses-Loans	7,000
Ending Balance September 30, 2023	225,000
Consumer Loans | Consumer
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	653
Unallocated
Activity in the allowance for credit losses - loans by loan class
Balance at beginning of year	365,273
Accounting Standards Update 2016-13
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		$ (175,000)
Accounting Standards Update 2016-13 | Cumulative effect of accounting change
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses	175,000
Ending Balance September 30, 2023	$ 175,000
Accounting Standards Update 2016-13 | Consumer
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		11,000
Accounting Standards Update 2016-13 | Commercial real estate | Commercial real estate
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		(818,000)
Accounting Standards Update 2016-13 | Commercial | Commercial and industrial
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		5,000
Accounting Standards Update 2016-13 | Commercial | Construction
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		2,000
Accounting Standards Update 2016-13 | Residential | One-to-four-family residential
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		1,137,000
Accounting Standards Update 2016-13 | Residential | Multi-family real estate
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		(147,000)
Accounting Standards Update 2016-13 | Unallocated
Activity in the allowance for credit losses - loans by loan class
Provision for credit losses		$ (365,000)