Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Numerator:
Net income	$ 2,614	$ 1,676	$ 98	$ 5,056
Shares used in computation — basic:
Weighted average common shares outstanding	32,759	31,993	32,544	31,359
Shares used in computation — diluted:
Shares used in computing basic net income per share	32,759	31,993	32,544	31,359
Dilutive effect of common shares outstanding subject to repurchase	313	110	305	222
Dilutive effect of options outstanding	28	52	38	72
Weighted average shares used in computing diluted net income per share	33,100	32,155	32,887	31,653
Net income per share — basic	$ 0.08	$ 0.05	$ 0.00	$ 0.16
Net income per share — diluted	$ 0.08	$ 0.05	$ 0.00	$ 0.16