Note 4 - Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Securities, continuous unrealized loss position, less than 12 months, fair value	$ 30,047,406	$ 39,551,825
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(1,348,739)	(307,898)
Securities, continuous unrealized loss position, 12 months or more, fair value		3,018,538
Securities, continuous unrealized loss position, 12 months or more, unrealized losses		(67,548)
Securities, continuous unrealized loss position, fair value	30,047,406	42,570,363
Securities, continuous unrealized loss position, unrealized losses	(1,348,739)	(375,446)
US States and Political Subdivisions Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	4,865,016	7,083,208
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(161,032)	(125,693)
Securities, continuous unrealized loss position, 12 months or more, fair value
Securities, continuous unrealized loss position, 12 months or more, unrealized losses
Securities, continuous unrealized loss position, fair value	4,865,016	7,083,208
Securities, continuous unrealized loss position, unrealized losses	(161,032)	(125,693)
US Government Agencies Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value		2,487,795
Securities, continuous unrealized loss position, less than 12 months, unrealized losses		(11,962)
Securities, continuous unrealized loss position, 12 months or more, fair value
Securities, continuous unrealized loss position, 12 months or more, unrealized losses
Securities, continuous unrealized loss position, fair value		2,487,795
Securities, continuous unrealized loss position, unrealized losses		(11,962)
Corporate Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	6,697,422	2,452,005
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(369,281)	(14,945)
Securities, continuous unrealized loss position, 12 months or more, fair value
Securities, continuous unrealized loss position, 12 months or more, unrealized losses
Securities, continuous unrealized loss position, fair value	6,697,422	2,452,005
Securities, continuous unrealized loss position, unrealized losses	(369,281)	(14,945)
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	12,527,985	9,416,669
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(680,781)	(29,392)
Securities, continuous unrealized loss position, 12 months or more, fair value
Securities, continuous unrealized loss position, 12 months or more, unrealized losses
Securities, continuous unrealized loss position, fair value	12,527,985	9,416,669
Securities, continuous unrealized loss position, unrealized losses	(680,781)	(29,392)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	5,956,983	18,112,148
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(137,645)	(125,906)
Securities, continuous unrealized loss position, 12 months or more, fair value		3,018,538
Securities, continuous unrealized loss position, 12 months or more, unrealized losses		(67,548)
Securities, continuous unrealized loss position, fair value	5,956,983	21,130,686
Securities, continuous unrealized loss position, unrealized losses	$ (137,645)	$ (193,454)