Note 4 - Securities - Available-for-sale Debt Securities (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Available-for-sale securities, amortized cost	$ 104,828,360	$ 88,102,659
Available-for-sale securities, gross unrealized gains	1,713,333	111,507
Available-for-sale securities, gross unrealized (losses)	(187,991)	(1,947,969)
Available-for-sale securities	106,353,702	86,266,197
US Government Agencies Debt Securities [Member]
Available-for-sale securities, amortized cost	1,499,752
Available-for-sale securities, gross unrealized gains
Available-for-sale securities, gross unrealized (losses)	(9,071)
Available-for-sale securities	1,490,681
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, amortized cost	30,172,564	34,470,648
Available-for-sale securities, gross unrealized gains	805,092	10,581
Available-for-sale securities, gross unrealized (losses)	(22,646)	(710,709)
Available-for-sale securities	30,955,010	33,770,520
Corporate Debt Securities [Member]
Available-for-sale securities, amortized cost	13,487,865	3,000,000
Available-for-sale securities, gross unrealized gains	164,686	18,927
Available-for-sale securities, gross unrealized (losses)	(13,115)
Available-for-sale securities	13,639,436	3,018,927
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities, amortized cost	48,704,459	50,632,011
Available-for-sale securities, gross unrealized gains	734,188	81,999
Available-for-sale securities, gross unrealized (losses)	(142,975)	(1,237,260)
Available-for-sale securities	49,295,672	$ 49,476,750
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Available-for-sale securities, amortized cost	10,963,720
Available-for-sale securities, gross unrealized gains	9,367
Available-for-sale securities, gross unrealized (losses)	(184)
Available-for-sale securities	$ 10,972,903

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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