Note 4 - Earnings Per Share - Calculation of Income (Loss) Per Shares (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Apr. 01, 2018
Net income	$ 7,059	$ 15,084
Weighted Average Shares Outstanding (in shares)	59,065	59,069
Participating Securities (in shares)	567	602
Shares for Basic Earnings Per Share (in shares)	59,632	59,671
Dilutive Effect of Stock Options (in shares)	10	46
Shares for Diluted Earnings Per Share (in shares)	59,642	59,717
Participating Securities [Member]
Net income	$ 100	$ 200