Note 13 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	$ 43,049,261	$ 34,121,642
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Federal Home Loan Bank stock	3,241,500	5,387,200
Mortgage loans held for sale	2,847,255	1,516,849
Interest receivable	3,773,210	3,390,944
Held-to-maturity securities		11,794
Financial liabilities:
Deposits	806,831,336	749,618,822
Federal Home Loan Bank advances	52,100,000	105,300,000
Interest payable	949,953	821,811
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	760,545,644	778,298,606
Financial liabilities:
Subordinated debentures	21,738,863	21,760,829
Note payable to Bank	5,000,000	5,000,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	43,049,261	34,121,642
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Federal Home Loan Bank stock	3,241,500	5,387,200
Mortgage loans held for sale	2,847,255	1,516,849
Interest receivable	3,773,210	3,390,944
Held-to-maturity securities		11,850
Financial liabilities:
Deposits	805,854,110	747,903,071
Federal Home Loan Bank advances	52,122,885	105,325,386
Interest payable	949,953	821,811
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Loans, net	762,879,550	783,910,789
Financial liabilities:
Subordinated debentures	21,738,863	21,760,829
Note payable to Bank	$ 5,000,000	$ 5,000,000