Note 8 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effective Income Tax Rate Reconciliation, Percent	37.40%	38.00%	32.90%	38.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount			$ 13.6
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 22.9		22.9
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	5.2		5.2
Other Noncurrent Liabilities [Member]
Unrecognized Tax Benefits	$ 35.2		$ 35.2