Note 8 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	25.10%	26.50%
Unrecognized Tax Benefits, Ending Balance	$ 68.2
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	58.8
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	$ 6.4