Note 8 - Fair Value - Estimated Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Fair value, available for sale	$ 162,126,265	$ 164,084,673
Fair value, held to maturity	18,975,422
Fair value hedge in other assets	69,127,662	69,920,575
Securities held to maturity	18,975,422
Reported Value Measurement [Member]
Federal Reserve Bank advances	54,000,000	33,000,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	25,633,230	44,690,337
Noninterest-bearing deposits	115,416,221	115,284,706
Securities sold under repurchase agreements	5,600,380	6,760,493
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Certificates of deposit in other banks	100,000	100,000
Accrued interest receivable	2,235,859	2,180,734
Fair value, available for sale	162,126,265	164,084,673
Fair value, held to maturity	17,328,604	17,293,422
Equity security	507,743	507,130
Restricted stock, at cost	920,900	863,500
Bank owned life insurance	15,021,074	14,930,754
Fair value hedge in other assets	205,349	0
Securities held to maturity	17,328,604	17,293,422
Interest-bearing deposits	540,561,366	565,678,145
Federal Home Loan Bank advances	5,000,000	5,000,000
Long-term debt, net	12,741,562	13,212,378
Accrued interest payable	1,404,170	1,482,773
Fair value hedge in other liabilities	655,975	1,563,527
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair value, held to maturity	2,870,200	2,870,200
Securities held to maturity	2,870,200	2,870,200
Loans, net	537,080,607	523,308,044
Estimate of Fair Value Measurement [Member]
Federal Reserve Bank advances	53,712,875	32,996,852
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	25,633,230	44,690,337
Noninterest-bearing deposits	115,416,221	115,284,706
Securities sold under repurchase agreements	5,600,380	6,760,493
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Certificates of deposit in other banks	100,000	100,000
Accrued interest receivable	2,235,859	2,180,734
Fair value, available for sale	162,126,265	164,084,673
Fair value, held to maturity	16,073,552	16,193,020
Equity security	507,743	507,130
Restricted stock, at cost	920,900	863,500
Bank owned life insurance	15,021,074	14,930,754
Fair value hedge in other assets	205,349	0
Securities held to maturity	16,073,552	16,193,020
Interest-bearing deposits	540,811,366	566,925,060
Federal Home Loan Bank advances	4,806,000	4,754,000
Long-term debt, net	11,833,366	12,428,000
Accrued interest payable	1,404,170	1,482,773
Fair value hedge in other liabilities	655,975	1,563,527
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair value, held to maturity	2,870,200	2,870,200
Securities held to maturity	2,870,200	2,870,200
Loans, net	$ 516,778,960	$ 507,138,253