Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012
Earnings Per Share
Net income	$ 20,034	$ 14,320
Shares used in computing basic earnings per share	42,186,000	42,458,000
Effect of dilutive securities:
Stock options and other stock-based awards (in shares)	924,000	1,392,000
Shares used in computing diluted earnings per share	43,110,000	43,850,000
Earnings per share:
Basic (in dollars per share)	$ 0.47	$ 0.34
Diluted (in dollars per share)	$ 0.46	$ 0.33
Shares excluded from computation of diluted earning per share	600,000	300,000