Note 14 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	$ 34,121,642	$ 37,406,930
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Held-to-maturity securities	11,794	16,457
Federal Home Loan Bank stock	5,387,200	4,597,500
Mortgage loans held for sale	1,516,849	1,921,819
Interest receivable	3,390,944	2,449,847
Financial liabilities:
Deposits	749,618,822	607,364,350
FHLB advances	105,300,000	94,300,000
Interest payable	821,811	295,543
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	778,298,606	629,605,009
Financial liabilities:
Subordinated debentures	21,760,829	15,465,000
Note payable to Bank	5,000,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	34,121,642	37,406,930
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Held-to-maturity securities	11,850	16,729
Federal Home Loan Bank stock	5,387,200	4,597,500
Mortgage loans held for sale	1,516,849	1,921,819
Interest receivable	3,390,944	2,449,847
Financial liabilities:
Deposits	747,903,071	606,548,280
FHLB advances	105,325,386	94,417,733
Interest payable	821,811	295,543
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	783,910,789	627,498,508
Financial liabilities:
Subordinated debentures	21,760,829	15,465,000
Note payable to Bank	$ 5,000,000