Note 12 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	$ 30,357,247	$ 37,406,930
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Held-to-maturity securities	14,111	16,457
Federal Home Loan Bank stock	4,791,200	4,597,500
Mortgage loans held for sale	1,771,560	1,921,819
Interest receivable	2,996,175	2,449,847
Deposits	764,771,510	607,364,350
Federal Home Loan Bank advances	90,400,000	94,300,000
Notes payable	5,000,000
Interest payable	711,911	295,543
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	772,517,090	629,605,009
Subordinated debentures	21,804,760	15,465,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	30,357,247	37,406,930
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Held-to-maturity securities	14,285	16,729
Federal Home Loan Bank stock	4,791,200	4,597,500
Mortgage loans held for sale	1,771,560	1,921,819
Interest receivable	2,996,175	2,449,847
Deposits	762,555,564	606,548,280
Federal Home Loan Bank advances	90,425,438	94,417,733
Notes payable	5,000,000
Interest payable	711,911	295,543
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	772,012,078	627,498,508
Subordinated debentures	$ 21,804,760	$ 15,465,000