Note 1 - Summary of Significant Accounting Policies - Other Comprehensive Earnings (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Unrealized holding gains arising during the period, pre-tax	$ 551,140	$ 890,152	$ 2,836,794	$ 4,333,205
Reclassification adjustment for (gains) included in net earnings, pre-tax	(67,102)	(89,262)	(411,651)	(238,405)
Total other comprehensive earnings, pre-tax	484,038	800,890	2,425,143	4,094,800
Unrealized holding gains arising during the period, tax	(57,292)	(116,415)	(256,869)	(721,632)
Reclassification adjustment for (gains) included in net earnings, tax	14,092	18,745	86,447	50,065
Total other comprehensive earnings, tax	(43,200)	(97,670)	(170,422)	(671,567)
Unrealized holding gains arising during the period, after-tax	493,848	773,737	2,579,925	3,611,573
Reclassification adjustment for (gains) included in net earnings, after tax	(53,010)	(70,517)	(325,204)	(188,340)
Total other comprehensive earnings, after-tax	$ 440,838	$ 703,220	$ 2,254,721	$ 3,423,233