Net Income Per Share (Schedule Of Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income	$ (31,934)	$ 20,794	$ 14,582	$ 15,994	$ 22,109	$ 21,119	$ 16,034	$ 16,589	$ 19,436	$ 75,851	$ 48,584
Weighted average shares outstanding: Basic (in shares)									32,097	32,758	33,161
Dilutive potential common shares (in shares)									947	970	627
Weighted average shares outstanding: Total (in shares)									33,044	33,728	33,788
Basic net income per share (in dollars per share)	$ (1.02)	$ 0.66	$ 0.45	$ 0.49	$ 0.67	$ 0.64	$ 0.49	$ 0.51	$ 0.61	$ 2.32	$ 1.47
Diluted net income per share (in dollars per share)	$ (1.02)	$ 0.64	$ 0.44	$ 0.47	$ 0.65	$ 0.62	$ 0.48	$ 0.50	$ 0.59	$ 2.25	$ 1.44
Anti-dilutive employee stock-based awards, excluded(in shares)									279	258	1,807