Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Earnings Per Share
Net income	$ 7,575	$ 14,279	$ 13,953	$ 22,389
Shares used in computing basic earnings per share	42,823	43,462	42,617	43,271
Effect of dilutive securities:
Stock options and other stock-based awards (in shares)	638	756	688	866
Shares used in computing diluted earnings per share	43,461	44,218	43,305	44,137
Earnings per share:
Basic (in dollars per share)	$ 0.18	$ 0.33	$ 0.33	$ 0.52
Diluted (in dollars per share)	$ 0.17	$ 0.32	$ 0.32	$ 0.51
Shares excluded from computation of diluted earning per share	100	100	100	200