Note 3 - Investment Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	$ 114,750,055
Securities held to maturity, less than 12 months, gross unrealized losses	(2,187,206)
Securities held to maturity, 12 months or more, fair value	69,412,341
Securities held to maturity, 12 months or more, gross unrealized losses	(4,616,191)
Securities held to maturity, fair value	184,162,396
Securities held to maturity, gross unrealized losses	(6,803,397)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	46,979,959	$ 128,656,909
Securities available for sale, less than 12 months, gross unrealized losses	(580,194)	(1,138,843)
Securities available for sale, 12 months or more, fair value	179,071,727	71,569,641
Securities available for sale, 12 months or more, gross unrealized losses	(5,536,124)	(1,761,568)
Securities available for sale, fair value	226,051,686	200,226,550
Securities available for sale, gross unrealized losses	(6,116,318)	(2,900,411)
US States and Political Subdivisions Debt Securities
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	114,200,687	23,750,826
Securities held to maturity, less than 12 months, gross unrealized losses	(2,186,574)	(354,460)
Securities held to maturity, 12 months or more, fair value	69,412,341	72,611,780
Securities held to maturity, 12 months or more, gross unrealized losses	(4,616,191)	(2,133,659)
Securities held to maturity, fair value	183,613,028	96,362,606
Securities held to maturity, gross unrealized losses	(6,802,765)	(2,488,119)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	28,356,204	10,229,337
Securities available for sale, less than 12 months, gross unrealized losses	(394,235)	(41,151)
Securities available for sale, 12 months or more, fair value	15,932,376	9,997,433
Securities available for sale, 12 months or more, gross unrealized losses	(308,750)	(169,949)
Securities available for sale, fair value	44,288,580	20,226,770
Securities available for sale, gross unrealized losses	(702,985)	(211,100)
US Government Agencies Debt Securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value	1,565,136	28,576,258
Securities available for sale, less than 12 months, gross unrealized losses	(33,278)	(200,022)
Securities available for sale, 12 months or more, fair value	29,605,388	3,640,477
Securities available for sale, 12 months or more, gross unrealized losses	(744,385)	(149,945)
Securities available for sale, fair value	31,170,524	32,216,735
Securities available for sale, gross unrealized losses	(777,663)	(349,967)
Residential Mortgage Backed Securities
Securities available for sale:
Securities available for sale, less than 12 months, fair value	12,809,544	88,927,779
Securities available for sale, less than 12 months, gross unrealized losses	(147,592)	(871,855)
Securities available for sale, 12 months or more, fair value	133,533,963	57,931,731
Securities available for sale, 12 months or more, gross unrealized losses	(4,482,989)	(1,441,674)
Securities available for sale, fair value	146,343,507	146,859,510
Securities available for sale, gross unrealized losses	(4,630,581)	(2,313,529)
Other Securities
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	549,368
Securities held to maturity, less than 12 months, gross unrealized losses	(632)
Securities held to maturity, fair value	549,368
Securities held to maturity, gross unrealized losses	(632)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	4,249,075	923,535
Securities available for sale, less than 12 months, gross unrealized losses	(5,089)	(25,815)
Securities available for sale, fair value	4,249,075	923,535
Securities available for sale, gross unrealized losses	$ (5,089)	$ (25,815)

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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