Note 1 - Summary of Significant Accounting Policies - Other Comprehensive Earnings (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Unrealized holding gains (losses) arising during the period, pre tax	$ (3,836,298)	$ (4,315,110)	$ (2,835,001)	$ (15,659,030)
Unrealized holding gains (losses) arising during the period, tax	805,622	906,173	595,350	3,288,396
Unrealized holding gains (losses) arising during the period, after tax	(3,030,676)	(3,408,937)	(2,239,651)	(12,370,634)
Reclassification adjustment for losses (gains) included in net earnings, pre-tax	6,863	0	58,761	628
Reclassification adjustment for losses (gains) included in net earnings, tax	(1,441)	0	(12,340)	(132)
Reclassification adjustment for losses (gains) included in net earnings, after-tax	5,422	0	46,421	496
Total other comprehensive earnings (loss), pre-tax	(3,829,435)	(4,315,110)	(2,776,240)	(15,658,402)
Total other comprehensive earnings (loss), tax	804,181	906,173	583,010	3,288,264
Total other comprehensive earnings (loss)	$ (3,025,254)	$ (3,408,937)	$ (2,193,230)	$ (12,370,138)