Note 9 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Financial assets:
Federal Home Loan Bank stock	$ 4,577,500	$ 4,611,000
Mortgage loans held for sale	1,903,062	2,183,633
Loans, net	608,159,460	538,273,640
Interest receivable	2,060,646	1,947,063
Cash and cash equivalents	10,747,347	9,088,441	$ 9,798,780	$ 18,774,419
Held-to-maturity securities	20,954	27,528
Financial liabilities:
Interest payable	213,907	207,833
Deposits	567,013,636	505,362,750
Subordinated debentures	15,465,000	15,465,000
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	10,747,347	9,088,441
Cash and cash equivalents	10,747,347	9,088,441
Fair Value, Inputs, Level 2 [Member]
Financial assets:
Federal Home Loan Bank stock	4,577,500	4,611,000
Federal Home Loan Bank stock	4,577,500	4,611,000
Mortgage loans held for sale	1,903,062	2,183,633
Mortgage loans held for sale	1,903,062	2,183,633
Interest receivable	2,060,646	1,947,063
Held-to-maturity securities	20,954	27,528
Held-to-maturity securities	21,506	28,153
Financial liabilities:
Interest payable	213,907	207,833
Deposits	567,013,636	505,362,750
Deposits	566,365,967	504,829,161
Federal Home Loan Bank advances	93,800,000	95,700,000
Federal Home Loan Bank advances	94,109,786	95,764,840
Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	608,159,460	538,273,640
Loans, net	611,060,521	537,645,692
Financial liabilities:
Subordinated debentures	15,465,000	15,465,000
Subordinated debentures	$ 15,465,000	$ 15,465,000