Net Income Per Share - Basic and Diluted Net Income (loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Numerator:
Net income	$ 24,741	$ 14,341
Shares used in computation — basic:
Weighted average common shares outstanding	36,723	33,061
Shares used in computation — diluted:
Shares used in computing basic net income per share	36,723	33,061
Dilutive effect of common shares outstanding subject to repurchase	761	793
Dilutive effect of options outstanding	7	11
Weighted average shares used in computing diluted net income per share	37,491	33,865
Net income per share — basic	$ 0.67	$ 0.43
Net income per share — diluted	$ 0.66	$ 0.42