Note 9 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	$ 10,721,184	$ 9,088,441
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Held-to-maturity securities, approximate fair value	18,424	27,528
Federal Home Loan Bank stock	4,137,500	4,611,000
Mortgage loans held for sale	2,516,520	2,183,633
Interest receivable	2,164,278	1,947,063
Financial liabilities:
Deposits	584,088,617	505,362,750
Federal Home Loan Bank advances	82,800,000	95,700,000
Interest payable	253,045	207,833
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	616,884,052	538,273,640
Financial liabilities:
Subordinated debentures	15,465,000	15,465,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	10,721,184	9,088,441
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Held-to-maturity securities, approximate fair value	18,582	28,153
Federal Home Loan Bank stock	4,137,500	4,611,000
Mortgage loans held for sale	2,516,520	2,183,633
Interest receivable	2,164,278	1,947,063
Financial liabilities:
Deposits	583,406,521	504,829,161
Federal Home Loan Bank advances	83,002,996	95,764,840
Interest payable	253,045	207,833
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	613,749,211	537,645,692
Financial liabilities:
Subordinated debentures	$ 15,465,000	$ 15,465,000