Note 4 - Earnings Per Share - Calculation of Income (Loss) Per Shares (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Net Income	$ 20,602	$ 20,938	$ 35,686	$ 29,485
Shares for Basic Earnings Per Share (in shares)	59,493	62,789	59,582	63,432
Dilutive Effect of Stock Options (in shares)	45	43	45	42
Shares for Diluted Earnings Per Share (in shares)	59,538	62,832	59,627	63,474
Participating Securities [Member]
Net Income	$ 200	$ 200	$ 300	$ 300
Weighted Average Shares Outstanding (in shares)	58,910	62,305	58,999	62,948
Participating Securities (in shares)	583	484	583	484