Note 10 - Income Taxes (Details Textual) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Unrecognized Tax Benefits, Ending Balance	$ 28.6		$ 28.9
Liability for Uncertainty in Income Taxes, Current	2.1		1.4
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	2.1
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total	0.5	$ 0.7
Income Tax Expense (Benefit) on Reversal of Interest and Penalties	0.7	$ 0.3
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	$ 4.7		$ 3.8