Note 13 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Assets Measured on Recurring Basis (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale securities	$ 98,793,658	$ 86,266,197
Fair Value, Recurring [Member]
Available-for-sale securities	98,794,000	86,266,000
Interest Rate Swaps	179,000	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	98,794,000	86,266,000
Interest Rate Swaps	179,000	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	32,579,399	33,770,520
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	32,580,000	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	32,580,000	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	6,036,377	3,018,927
Corporate Debt Securities [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	6,036,000	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	6,036,000	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	60,177,882	49,476,750
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Recurring [Member]
Available-for-sale securities	60,178,000	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	60,178,000	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