Net Income Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012
Basic net income per common share calculation
Net income	$ 18,904	$ 24,255	$ 60,263	$ 70,549
Net income allocated to participating securities				(20)
Net income attributable to common shareholders	$ 18,904	$ 24,255	$ 60,263	$ 70,529
Weighted average number of common shares used to compute basic net income per common share	57,427	58,762	57,447	58,645
Basic net income per common share (in dollars per share)	$ 0.33	$ 0.41	$ 1.05	$ 1.20