Note 3 - Securities - Available-for-sale Securities (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale securities, amortized cost	$ 83,948,214	$ 94,477,285
Available-for-sale securities, gross unrealized gains	312,727	139,155
Available-for-sale securities, gross unrealized (losses)	(1,055,746)	(2,217,205)
Available-for-sale securities, approximate fair value	83,205,195	92,399,235
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, amortized cost	34,012,067	39,357,506
Available-for-sale securities, gross unrealized gains	210,255	65,673
Available-for-sale securities, gross unrealized (losses)	(328,991)	(1,085,654)
Available-for-sale securities, approximate fair value	33,893,331	38,337,525
Corporate Debt Securities [Member]
Available-for-sale securities, amortized cost	3,000,000	7,003,986
Available-for-sale securities, gross unrealized gains	70,000	54,050
Available-for-sale securities, gross unrealized (losses)		(4,514)
Available-for-sale securities, approximate fair value	3,070,000	7,053,522
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities, amortized cost	46,936,147	48,115,793
Available-for-sale securities, gross unrealized gains	32,472	19,432
Available-for-sale securities, gross unrealized (losses)	(726,755)	(1,127,037)
Available-for-sale securities, approximate fair value	$ 46,241,864	$ 47,008,188

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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