Note 2 - Investment Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	$ 141,292,266
Securities held to maturity, less than 12 months, gross unrealized losses	(3,888,393)
Securities held to maturity, 12 months or more, fair value	61,121,755
Securities held to maturity, 12 months or more, gross unrealized losses	(3,827,871)
Securities held to maturity, fair value	202,414,021
Securities held to maturity, gross unrealized losses	(7,716,264)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	165,068,419	$ 128,656,909
Securities available for sale, less than 12 months, gross unrealized losses	(4,996,353)	(1,138,843)
Securities available for sale, 12 months or more, fair value	70,964,048	71,569,641
Securities available for sale, 12 months or more, gross unrealized losses	(3,312,235)	(1,761,568)
Securities available for sale, fair value	236,032,467	200,226,550
Securities available for sale, gross unrealized losses	(8,308,588)	(2,900,411)
US States and Political Subdivisions Debt Securities [Member]
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	140,257,617	23,750,826
Securities held to maturity, less than 12 months, gross unrealized losses	(3,873,043)	(354,460)
Securities held to maturity, 12 months or more, fair value	61,121,755	72,611,780
Securities held to maturity, 12 months or more, gross unrealized losses	(3,827,871)	(2,133,659)
Securities held to maturity, fair value	201,379,372	96,362,606
Securities held to maturity, gross unrealized losses	(7,700,914)	(2,488,119)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	36,033,296	10,229,337
Securities available for sale, less than 12 months, gross unrealized losses	(648,203)	(41,151)
Securities available for sale, 12 months or more, fair value	7,706,943	9,997,433
Securities available for sale, 12 months or more, gross unrealized losses	(225,890)	(169,949)
Securities available for sale, fair value	43,740,239	20,226,770
Securities available for sale, gross unrealized losses	(874,093)	(211,100)
US Government Agencies Debt Securities [Member]
Securities available for sale:
Securities available for sale, less than 12 months, fair value	31,724,483	28,576,258
Securities available for sale, less than 12 months, gross unrealized losses	(928,027)	(200,022)
Securities available for sale, 12 months or more, fair value	3,532,286	3,640,477
Securities available for sale, 12 months or more, gross unrealized losses	(181,197)	(149,945)
Securities available for sale, fair value	35,256,769	32,216,735
Securities available for sale, gross unrealized losses	(1,109,224)	(349,967)
Residential Mortgage Backed Securities [Member]
Securities available for sale:
Securities available for sale, less than 12 months, fair value	93,074,220	88,927,779
Securities available for sale, less than 12 months, gross unrealized losses	(3,402,034)	(871,855)
Securities available for sale, 12 months or more, fair value	59,724,819	57,931,731
Securities available for sale, 12 months or more, gross unrealized losses	(2,905,148)	(1,441,674)
Securities available for sale, fair value	152,799,039	146,859,510
Securities available for sale, gross unrealized losses	(6,307,182)	(2,313,529)
Other Securities [Member]
Securities held to maturity:
Securities held to maturity, less than 12 months, fair value	1,034,649
Securities held to maturity, less than 12 months, gross unrealized losses	(15,350)
Securities held to maturity, fair value	1,034,649
Securities held to maturity, gross unrealized losses	(15,350)
Securities available for sale:
Securities available for sale, less than 12 months, fair value	4,236,420	923,535
Securities available for sale, less than 12 months, gross unrealized losses	(18,089)	(25,815)
Securities available for sale, fair value	4,236,420	923,535
Securities available for sale, gross unrealized losses	$ (18,089)	$ (25,815)

No definition available.

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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 investments in debt and equity securities classified as available-for-sale in a continuous loss position.

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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 less than twelve months.

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No definition available.

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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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