Note 4 - Securities - Available-for-sale Debt Securities (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Available-for-sale securities, amortized cost	$ 137,926,282	$ 117,152,760
Available-for-sale securities, gross unrealized gains	3,431,911	1,468,000
Available-for-sale securities, gross unrealized (losses)	(1,348,739)	(375,446)
Available-for-sale securities	140,009,454	118,245,314
US Government Agencies Debt Securities [Member]
Available-for-sale securities, amortized cost	2,499,762	2,499,755
Available-for-sale securities, gross unrealized gains	15,578
Available-for-sale securities, gross unrealized (losses)		(11,962)
Available-for-sale securities	2,515,340	2,487,793
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, amortized cost	43,680,501	35,625,038
Available-for-sale securities, gross unrealized gains	1,528,568	675,382
Available-for-sale securities, gross unrealized (losses)	(161,032)	(125,693)
Available-for-sale securities	45,048,037	36,174,727
Corporate Debt Securities [Member]
Available-for-sale securities, amortized cost	21,655,250	15,395,190
Available-for-sale securities, gross unrealized gains	255,018	154,942
Available-for-sale securities, gross unrealized (losses)	(369,281)	(14,945)
Available-for-sale securities	21,540,987	15,535,187
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Available-for-sale securities, amortized cost	14,239,775	13,788,728
Available-for-sale securities, gross unrealized gains	1,638	52,035
Available-for-sale securities, gross unrealized (losses)	(680,781)	(29,392)
Available-for-sale securities	13,560,632	13,811,371
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities, amortized cost	55,850,994	49,844,049
Available-for-sale securities, gross unrealized gains	1,631,109	585,641
Available-for-sale securities, gross unrealized (losses)	(137,645)	(193,454)
Available-for-sale securities	$ 57,344,458	$ 50,236,236

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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