Note 4 - Securities - Available-for-sale Debt Securities (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Available-for-sale securities, amortized cost	$ 94,195,850	$ 88,102,659
Available-for-sale securities, gross unrealized gains	1,070,351	111,507
Available-for-sale securities, gross unrealized (losses)	(234,980)	(1,947,969)
Available-for-sale securities	95,031,221	86,266,197
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, amortized cost	27,758,660	34,470,648
Available-for-sale securities, gross unrealized gains	369,243	10,581
Available-for-sale securities, gross unrealized (losses)	(15,228)	(710,709)
Available-for-sale securities	28,112,675	33,770,520
Corporate Debt Securities [Member]
Available-for-sale securities, amortized cost	10,049,914	3,000,000
Available-for-sale securities, gross unrealized gains	55,339	18,927
Available-for-sale securities, gross unrealized (losses)	(20,013)
Available-for-sale securities	10,085,240	3,018,927
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities, amortized cost	56,387,276	50,632,011
Available-for-sale securities, gross unrealized gains	645,769	81,999
Available-for-sale securities, gross unrealized (losses)	(199,739)	(1,237,260)
Available-for-sale securities	$ 56,833,306	$ 49,476,750

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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