Note 13 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Assets Measured on Recurring Basis (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Available-for-sale securities	$ 95,031,221	$ 86,266,197
Fair Value, Recurring [Member]
Available-for-sale securities	95,031,000	86,266,000
Interest rate swaps	1,571,000	1,272,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
Interest rate swaps
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	95,031,000	86,266,000
Interest rate swaps	1,571,000	1,272,000
Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
Interest rate swaps
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	28,112,675	33,770,520
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	28,113,000	33,770,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	28,113,000	33,770,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
Corporate Debt Securities [Member]
Available-for-sale securities	10,085,240	3,018,927
Corporate Debt Securities [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	10,085,000	3,019,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	10,085,000	3,019,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities	56,833,306	49,476,750
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	56,833,000	49,477,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	56,833,000	49,477,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Available-for-sale securities