Note 11 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Expense (Benefit), Total	$ 4,484	$ 6,438	$ 12,817	$ 17,724
Effective Income Tax Rate Reconciliation, Percent, Total	17.60%	32.80%	18.30%	32.10%
Effective Income Tax Rate, Increase (Decrease), Percentage	(15.20%)		(13.80%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%		21.00%
Unrecognized Tax Benefits, Ending Balance	$ 3,900		$ 3,900		$ 4,200