Loans and Allowance for Loan Losses - Categories of loans (Details) - USD ($)	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021	Jun. 30, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 82,922,637	$ 82,267,595
Less:
Undisbursed loans in process	3,589,117	4,324,320
Net deferred loan fees	12,488	10,203
Allowance for loan losses	222,884	222,884	$ 222,884	$ 222,884
Net loans	79,098,148	77,710,188
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,972,791	5,136,407
Less:
Allowance for loan losses	19,694	20,643	26,165	27,506
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	66,123,917	65,638,154
Less:
Allowance for loan losses	175,740	177,830	172,441	176,498
Multifamily real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	711,402	718,911
Less:
Allowance for loan losses	1,879	1,926
Agricultural real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,015,564	3,450,672
Less:
Allowance for loan losses	15,904	13,868	11,853	8,334
Construction and land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	5,517,796	6,006,613
Less:
Allowance for loan losses	6,087	5,477	9,765	7,723
Home equity line of credit (HELOC)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	494,128	264,421
Less:
Allowance for loan losses	1,196	1,306	1,253	577
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	301,945	339,094
Less:
Allowance for loan losses	1,304	709	655	1,437
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	785,094	713,323
Less:
Allowance for loan losses	$ 1,080	$ 1,125	$ 752	$ 809