Note 10 - Income Taxes - Difference Between Statutory and Effective Tax Rates (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	3.50%	3.50%	0.80%
Excess tax benefits from stock-based compensation arrangements	(1.00%)	(1.10%)	(0.70%)
Change in cash surrender value of life insurance	0.20%	(0.80%)	(0.80%)
Tax credits	(0.20%)	(0.30%)	(5.50%)
Kentucky state income tax enactments	0.00%	0.00%	(2.20%)
Tax exempt interest income	(0.60%)	(0.40%)	(0.30%)
Non-deductible merger expenses	0.10%	0.40%	0.00%
Insurance captive	(0.30%)	(0.20%)	0.00%
Amortization of investment in tax credit partnerships	0.10%	0.10%	1.00%
Other, net	(0.20%)	(0.40%)	(0.20%)
Effective tax rate	22.60%	21.80%	13.10%