Note 13 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Interest-bearing demand deposits in other financial institutions	$ 78,226,550	$ 87,557,842
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	84,343,930	92,671,909
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Interest-bearing demand deposits in other financial institutions	3,534,996	250,000
Federal Home Loan Bank stock	3,212,100	3,757,500
Mortgage loans held for sale	1,980,896	2,786,564
Interest receivable	3,533,856	3,511,875
Deposits	849,535,941	821,406,532
Federal Home Loan Bank advances	50,000,000	65,000,000
Interest payable	799,338	793,746
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	721,062,691	720,732,402
Subordinated debentures	15,465,000	15,465,000
Note payable to bank	11,200,000	11,200,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	84,343,930	92,671,909
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Interest-bearing demand deposits in other financial institutions	3,535,959	250,315
Federal Home Loan Bank stock	3,212,100	3,757,500
Mortgage loans held for sale	1,980,896	2,786,564
Interest receivable	3,533,856	3,511,875
Deposits	851,761,814	822,046,988
Federal Home Loan Bank advances	49,958,347	66,015,635
Interest payable	799,338	793,746
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	722,567,482	723,363,117
Subordinated debentures	15,465,000	15,465,000
Note payable to bank	$ 11,200,000	$ 11,200,000