Loans - Activity in the allowance for loan losses by portfolio segment (Details) - USD ($)	3 Months Ended			9 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Mar. 31, 2023	Jun. 30, 2023
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	$ 2,059,471	$ 2,058,869	$ 2,195,050	$ 2,195,050
Charge-offs			(136,753)
Recoveries	618	602	572
Provision for Credit Losses	0
Balance at end of year	2,060,089	2,059,471	2,058,869	2,060,089
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	2,060,089			2,060,089	$ 2,158,590
Loans and Leases Receivable, Allowance	2,060,089	2,059,471	2,058,869	2,060,089	2,158,590
Loans - Individually evaluated for impairment	119,883			119,883	117,103
Loans - Collectively evaluated for impairment	204,076,851			204,076,851	199,818,743
Loans and Leases Receivable, Gross	204,196,734			204,196,734	199,935,846
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	603	620	601	601
Recoveries	618	602	572
Provision for Credit Losses	(506)	(619)	(553)
Balance at end of year	715	603	620	715
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	715			715
Loans and Leases Receivable, Allowance	715	603	620	715
Loans - Collectively evaluated for impairment	3,143,433			3,143,433
Loans and Leases Receivable, Gross	3,143,433			3,143,433
Commercial real estate | Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	1,285,009	1,564,021	1,591,644	1,591,644
Charge-offs			(136,753)
Provision for Credit Losses	(48,960)	(279,012)	109,130
Balance at end of year	1,236,049	1,285,009	1,564,021	1,236,049
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	1,236,049			1,236,049	1,196,479
Loans and Leases Receivable, Allowance	1,236,049	1,285,009	1,564,021	1,236,049	1,196,479
Loans - Collectively evaluated for impairment	84,944,122			84,944,122	84,580,946
Loans and Leases Receivable, Gross	84,944,122			84,944,122	84,580,946
Commercial
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans and Leases Receivable, Gross					93,364,410
Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans and Leases Receivable, Gross					84,580,946
Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	21,338	27,398	32,701	32,701
Provision for Credit Losses	(2,772)	(6,060)	(5,303)
Balance at end of year	18,566	21,338	27,398	18,566
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	18,566			18,566	17,711
Loans and Leases Receivable, Allowance	18,566	21,338	27,398	18,566	17,711
Loans - Collectively evaluated for impairment	7,210,087			7,210,087	6,878,209
Loans and Leases Receivable, Gross	7,210,087			7,210,087	6,878,209
Commercial | Construction
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	17,606	24,791	55,029	55,029
Provision for Credit Losses	(3,430)	(7,185)	(30,238)
Balance at end of year	14,176	17,606	24,791	14,176
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	14,176			14,176	6,302
Loans and Leases Receivable, Allowance	14,176	17,606	24,791	14,176	6,302
Loans - Collectively evaluated for impairment	7,520,505			7,520,505	1,905,255
Loans and Leases Receivable, Gross	7,520,505			7,520,505	1,905,255
Residential | One-to-four-family residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	208,286	222,284	263,951	263,951
Provision for Credit Losses	1,822	(13,998)	(41,667)
Balance at end of year	210,108	208,286	222,284	210,108
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	210,108			210,108	206,771
Loans and Leases Receivable, Allowance	210,108	208,286	222,284	210,108	206,771
Loans - Individually evaluated for impairment	119,883			119,883	117,103
Loans - Collectively evaluated for impairment	60,452,863			60,452,863	59,445,715
Loans and Leases Receivable, Gross	60,572,746			60,572,746	59,562,818
Residential | Multi-family real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	195,757	216,133	233,371	233,371
Provision for Credit Losses	62,340	(20,376)	(17,238)
Balance at end of year	258,097	195,757	216,133	258,097
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	258,097			258,097	365,401
Loans and Leases Receivable, Allowance	258,097	195,757	216,133	258,097	365,401
Loans - Collectively evaluated for impairment	40,805,841			40,805,841	44,183,871
Loans and Leases Receivable, Gross	40,805,841			40,805,841	44,183,871
Consumer Loans
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans and Leases Receivable, Allowance					2,000
Consumer Loans | Consumer
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment					653
Loans and Leases Receivable, Allowance					653
Loans - Collectively evaluated for impairment					2,824,747
Loans and Leases Receivable, Gross					2,824,747
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	330,872	3,622	17,753	17,753
Provision for Credit Losses	(8,494)	327,250	(14,131)
Balance at end of year	322,378	330,872	3,622	322,378
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	322,378			322,378	365,273
Loans and Leases Receivable, Allowance	$ 322,378	$ 330,872	$ 3,622	$ 322,378	$ 365,273