Note 15 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Interest-bearing demand deposits in other financial institutions	$ 87,557,842	$ 28,302,687
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	92,671,909	34,121,642
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Interest-bearing demand deposits in other financial institutions	250,000
Held-to-maturity securities		11,794
Federal Home Loan Bank stock	3,757,500	5,387,200
Mortgage loans held for sale	2,786,564	1,516,849
Interest receivable	3,511,875	3,390,944
Deposits	821,406,532	749,618,822
FHLB advances	65,000,000	105,300,000
Interest payable	793,746	821,811
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	720,732,402	778,298,606
Subordinated debentures	15,465,000	21,760,829
Note payable to bank	11,200,000	5,000,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	92,671,909	34,121,642
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Interest-bearing demand deposits in other financial institutions	250,315
Held-to-maturity securities		11,850
Federal Home Loan Bank stock	3,757,500	5,387,200
Mortgage loans held for sale	2,786,564	1,516,849
Interest receivable	3,511,875	3,390,944
Deposits	822,046,988	747,903,071
FHLB advances	65,015,635	105,325,386
Interest payable	793,746	821,811
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	723,363,117	783,910,789
Subordinated debentures	15,465,000	21,760,829
Note payable to bank	$ 11,200,000	$ 5,000,000