Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2015	Sep. 27, 2014	Oct. 03, 2015	Sep. 27, 2014
Earnings Per Share
Net income	$ 9,975	$ 5,608	$ 23,928	$ 27,997
Shares used in computing basic earnings per share	42,331	43,112	42,522	43,218
Effect of dilutive securities:
Stock options and other stock-based awards (in shares)	464	703	613	812
Shares used in computing diluted earnings per share	42,795	43,815	43,135	44,030
Earnings per share:
Basic (in dollars per share)	$ 0.24	$ 0.13	$ 0.56	$ 0.65
Diluted (in dollars per share)	$ 0.23	$ 0.13	$ 0.55	$ 0.64
Shares excluded from computation of diluted earning per share	100	100	100	100