Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Earnings Per Share [Abstract]
Net income	$ 2,048	$ (1,123)	$ 4,053	$ 6,327
Shares used in computation - basic:
Weighted average common shares outstanding	28,451	27,656	28,265	24,851
Shares used in computation - diluted:
Shares used in computing basic net income per share	28,451	27,656	28,265	24,851
Dilutive effect of common shares outstanding subject to repurchase	241		365	265
Dilutive effect of options outstanding	287		249	377
Weighted average shares used in computing diluted net income per share	28,979	27,656	28,879	25,493
Net income per share - basic	$ 0.07	$ (0.04)	$ 0.14	$ 0.25
Net income per share - diluted	$ 0.07	$ (0.04)	$ 0.14	$ 0.25