Note 7 - Employee Benefit Plans (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan, Cost	$ 34.3	$ 32.5	$ 28.1
Deferred Compensation Liability, Current and Noncurrent	31.6	25.1
Other Current Assets [Member] | Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 31.6	$ 25.1