Note 13 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Interest-bearing time deposits at other financial institutions	$ 250,000	$ 250,000
Reported Value Measurement [Member]
Interest-bearing time deposits at other financial institutions	250,000	250,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	53,025,771	34,121,642
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Federal Home Loan Bank stock	3,157,500	5,387,200
Mortgage loans held for sale	1,914,419	1,516,849
Interest receivable	3,528,976	3,390,944
Deposits	802,477,539	749,618,822
Federal Home Loan Bank advances	50,000,000	105,300,000
Interest payable	967,815	821,811
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	751,190,822	778,298,606
Subordinated debentures	21,716,897	21,760,829
Note payable to Bank	5,000,000	5,000,000
Estimate of Fair Value Measurement [Member]
Interest-bearing time deposits at other financial institutions	250,215	250,116
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	53,025,771	34,121,642
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Federal Home Loan Bank stock	3,157,500	5,387,200
Mortgage loans held for sale	1,914,419	1,516,849
Interest receivable	3,528,976	3,390,944
Deposits	802,574,177	747,903,071
Federal Home Loan Bank advances	50,009,611	105,325,386
Interest payable	967,815	821,811
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	763,285,223	783,910,789
Subordinated debentures	21,716,897	21,760,829
Note payable to Bank	$ 5,000,000	$ 5,000,000