Note 9 - Earnings Per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 6,372	$ 14,046	$ 14,331	$ 28,486
Basic (in shares)	83,923	84,101	83,778	84,338
Plus: net effect of dilutive stock options and restricted stock units (in shares)	1,807	752	1,808	1,655
Weighted average common shares outstanding-diluted (in shares)	85,730	84,853	85,586	85,993
Net income per common share -- basic (in dollars per share)	$ 0.08	$ 0.17	$ 0.17	$ 0.34
Net income per common share -- diluted (in dollars per share)	$ 0.07	$ 0.17	$ 0.17	$ 0.33