Note 9 - Earnings Per Share - Computation of 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	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Net income	$ 42,808	$ 30,802	$ 130,338	$ 77,243
Basic (in shares)	22,713	22,578	22,678	22,515
Effect of dilutive securities (in shares)	240	156	228	160
Diluted (in shares)	22,953	22,734	22,906	22,675
Earnings Per Share:
Basic earnings per share (in dollars per share)	$ 1.88	$ 1.36	$ 5.75	$ 3.43
Diluted earnings per share (in dollars per share)	$ 1.87	$ 1.35	$ 5.69	$ 3.41