Note 3 - Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Securities, continuous unrealized loss position, less than 12 months, fair value	$ 30,049,473	$ 39,551,825
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(314,249)	(307,898)
Securities, continuous unrealized loss position, 12 months or more, fair value	0	3,018,538
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0	(67,548)
Securities, continuous unrealized loss position, fair value	30,049,473	42,570,363
Securities, continuous unrealized loss position, unrealized losses	(314,249)	(375,446)
US Government Agencies Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	1,495,116	2,487,795
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(4,885)	(11,962)
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	1,495,116	2,487,795
Securities, continuous unrealized loss position, unrealized losses	(4,885)	(11,962)
US States and Political Subdivisions Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	4,011,492	7,083,208
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(26,991)	(125,693)
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	4,011,492	7,083,208
Securities, continuous unrealized loss position, unrealized losses	(26,991)	(125,693)
Corporate Debt Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	14,869,853	2,452,005
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(171,811)	(14,945)
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	14,869,853	2,452,005
Securities, continuous unrealized loss position, unrealized losses	(171,811)	(14,945)
Commercial Mortgage Backed Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	1,481,805
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(10,650)
Securities, continuous unrealized loss position, 12 months or more, fair value	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0
Securities, continuous unrealized loss position, fair value	1,481,805
Securities, continuous unrealized loss position, unrealized losses	(10,650)
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value		9,416,669
Securities, continuous unrealized loss position, less than 12 months, unrealized losses		(29,392)
Securities, continuous unrealized loss position, 12 months or more, fair value		0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses		0
Securities, continuous unrealized loss position, fair value		9,416,669
Securities, continuous unrealized loss position, unrealized losses		(29,392)
Residential Mortgage Backed Securities [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	2,391,511
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(25,747)
Securities, continuous unrealized loss position, 12 months or more, fair value	0
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0
Securities, continuous unrealized loss position, fair value	2,391,511
Securities, continuous unrealized loss position, unrealized losses	(25,747)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities, continuous unrealized loss position, less than 12 months, fair value	5,799,696	18,112,148
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(74,165)	(125,906)
Securities, continuous unrealized loss position, 12 months or more, fair value	0	3,018,538
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	0	(67,548)
Securities, continuous unrealized loss position, fair value	5,799,696	21,130,686
Securities, continuous unrealized loss position, unrealized losses	$ (74,165)	$ (193,454)