Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Earnings Per Share
Net income	$ 10,024	$ 11,255	$ 44,853	$ 22,667
Shares used in computing basic earnings per share	41,735,000	42,834,000	42,279,000	43,902,000
Effect of dilutive securities:
Stock options and other stock-based awards (in shares)	785,000	1,085,000	982,000	1,403,000
Shares used in computing diluted earnings per share	42,520,000	43,919,000	43,261,000	45,305,000
Earnings per share:
Basic (in dollars per share)	$ 0.24	$ 0.26	$ 1.06	$ 0.52
Diluted (in dollars per share)	$ 0.24	$ 0.26	$ 1.04	$ 0.50
Shares excluded from computation of diluted earning per share	800,000	1,400,000	900,000	500,000