Note 3 - Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Securities, continuous unrealized loss position, less than 12 months, fair value	$ 65,356,233	$ 30,049,473
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(2,019,152)	(314,249)
Securities, continuous unrealized loss position, 12 months or more, fair value	3,427,793	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	(90,317)	0
Securities, continuous unrealized loss position, fair value	68,784,026	30,049,473
Securities, continuous unrealized loss position, unrealized losses	(2,109,469)	(314,249)
US Government Agencies Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	6,984,688	1,495,116
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(293,249)	(4,885)
Securities, continuous unrealized loss position, 12 months or more, fair value	0	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0	0
Securities, continuous unrealized loss position, fair value	6,984,688	1,495,116
Securities, continuous unrealized loss position, unrealized losses	(293,249)	(4,885)
US States and Political Subdivisions Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	19,726,646	4,011,492
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(665,287)	(26,991)
Securities, continuous unrealized loss position, 12 months or more, fair value	940,820	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	(77,922)	0
Securities, continuous unrealized loss position, fair value	20,667,466	4,011,492
Securities, continuous unrealized loss position, unrealized losses	(743,209)	(26,991)
Corporate Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	15,201,566	14,869,853
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(390,164)	(171,811)
Securities, continuous unrealized loss position, 12 months or more, fair value	1,002,423	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	(3,928)	0
Securities, continuous unrealized loss position, fair value	16,203,989	14,869,853
Securities, continuous unrealized loss position, unrealized losses	(394,092)	(171,811)
Commercial Mortgage Backed Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	1,007,242	1,481,805
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(109)	(10,650)
Securities, continuous unrealized loss position, 12 months or more, fair value	1,484,550	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	(8,467)	0
Securities, continuous unrealized loss position, fair value	2,491,792	1,481,805
Securities, continuous unrealized loss position, unrealized losses	(8,576)	(10,650)
Residential Mortgage Backed Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	3,092,306	2,391,511
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(95,228)	(25,747)
Securities, continuous unrealized loss position, 12 months or more, fair value	0	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0	0
Securities, continuous unrealized loss position, fair value	3,092,306	2,391,511
Securities, continuous unrealized loss position, unrealized losses	(95,228)	(25,747)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	19,343,785	5,799,696
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(575,115)	(74,165)
Securities, continuous unrealized loss position, 12 months or more, fair value	0	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0	0
Securities, continuous unrealized loss position, fair value	19,343,785	5,799,696
Securities, continuous unrealized loss position, unrealized losses	$ (575,115)	$ (74,165)