Loans - Activity in the allowance for loan losses by portfolio segment (Details) - USD ($)	3 Months Ended
Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2022
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	$ 2,058,869	$ 2,195,050	$ 2,187,306	$ 2,186,182
Charge-offs		(136,753)
Recoveries	602	572	1,337	1,124
Balance at end of year	2,059,471	2,058,869	2,188,643	2,187,306
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	2,059,471		2,188,643		$ 2,195,050
Loans and Leases Receivable, Allowance	2,059,471	2,058,869	2,188,643	2,187,306	2,195,050
Loans - Individually evaluated for impairment	179,173		516,533		193,385
Loans - Collectively evaluated for impairment	194,578,729		158,066,006		187,707,089
Loans and Leases Receivable, Gross	194,757,902		158,582,539		187,900,474
Commercial real estate [Member] \| Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	1,564,021	1,591,644	1,223,850	1,036,301
Charge-offs		(136,753)
Provisions	(279,012)	109,130	64,577	187,549
Balance at end of year	1,285,009	1,564,021	1,288,427	1,223,850
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	1,285,009		1,288,427		1,591,644
Loans and Leases Receivable, Allowance	1,285,009	1,564,021	1,288,427	1,223,850	1,591,644
Loans - Individually evaluated for impairment			217,449
Loans - Collectively evaluated for impairment	85,612,836		62,815,351		80,603,153
Loans and Leases Receivable, Gross	85,612,836		63,032,800		80,603,153
Commercial [Member]
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans and Leases Receivable, Gross	100,856,113				99,964,364
Commercial [Member] \| Commercial real estate
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans and Leases Receivable, Gross	85,612,836				80,603,153
Commercial [Member] \| Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	27,398	32,701	68,497	157,533
Provisions	(6,060)	(5,303)	(19,488)	(89,036)
Balance at end of year	21,338	27,398	49,009	68,497
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	21,338		49,009		32,701
Loans and Leases Receivable, Allowance	21,338	27,398	49,009	68,497	32,701
Loans - Collectively evaluated for impairment	7,830,296		8,901,181		8,778,723
Loans and Leases Receivable, Gross	7,830,296		8,901,181		8,778,723
Commercial [Member] \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	24,791	55,029	50,646	59,649
Provisions	(7,185)	(30,238)	(2,866)	(9,003)
Balance at end of year	17,606	24,791	47,780	50,646
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	17,606		47,780		55,029
Loans and Leases Receivable, Allowance	17,606	24,791	47,780	50,646	55,029
Loans - Collectively evaluated for impairment	7,412,981		8,098,343		10,582,488
Loans and Leases Receivable, Gross	7,412,981		8,098,343		10,582,488
Residential [Member] \| One-to-four-family residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	222,284	263,951	356,257	409,395
Provisions	(13,998)	(41,667)	(14,346)	(53,138)
Balance at end of year	208,286	222,284	341,911	356,257
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	208,286		341,911		263,951
Loans and Leases Receivable, Allowance	208,286	222,284	341,911	356,257	263,951
Loans - Individually evaluated for impairment	179,173		299,084		193,385
Loans - Collectively evaluated for impairment	56,525,772		51,381,035		51,697,563
Loans and Leases Receivable, Gross	56,704,945		51,680,119		51,890,948
Residential [Member] \| Multi-family real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	216,133	233,371	86,482	134,216
Provisions	(20,376)	(17,238)	34,871	(47,734)
Balance at end of year	195,757	216,133	121,353	86,482
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	195,757		121,353		233,371
Loans and Leases Receivable, Allowance	195,757	216,133	121,353	86,482	233,371
Loans - Collectively evaluated for impairment	35,113,319		24,615,280		33,944,903
Loans and Leases Receivable, Gross	35,113,319		24,615,280		33,944,903
Consumer Loans [Member] \| Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	620	601	5,918	4,896
Recoveries	602	572	1,337	1,124
Provisions	(619)	(553)	(1,723)	(102)
Balance at end of year	603	620	5,532	5,918
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	603		5,532		601
Loans and Leases Receivable, Allowance	603	620	5,532	5,918	601
Loans - Collectively evaluated for impairment	2,083,525		2,254,816		2,100,259
Loans and Leases Receivable, Gross	2,083,525		2,254,816		2,100,259
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	3,622	17,753	395,656	384,192
Provisions	327,250	(14,131)	(61,025)	11,464
Balance at end of year	330,872	3,622	334,631	395,656
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	330,872		334,631		17,753
Loans and Leases Receivable, Allowance	$ 330,872	$ 3,622	$ 334,631	$ 395,656	$ 17,753

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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