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		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Numerator:
Net income	$ 18,960	$ 20,179	$ 43,701	$ 34,520
Shares used in computation — basic:
Weighted average common shares outstanding	38,802	33,433	37,763	33,247
Shares used in computation — diluted:
Shares used in computing basic net income per share	38,802	33,433	37,763	33,247
Dilutive effect of common shares outstanding subject to repurchase	489	622	649	749
Dilutive effect of options outstanding	6	9	6	21
Weighted average shares used in computing diluted net income per share	39,297	34,064	38,418	34,017
Net income per share — basic	$ 0.49	$ 0.60	$ 1.16	$ 1.04
Net income per share — diluted	$ 0.48	$ 0.59	$ 1.14	$ 1.01