Net Income Per Share - Computation of Basic and Diluted Net Income per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2016	Sep. 30, 2015	Sep. 28, 2016	Sep. 30, 2015
Numerator:
Net income	$ 5,211	$ 4,666	$ 17,921	$ 18,688
Denominator:
Weighted-average shares outstanding—basic	38,415,189	38,275,317	38,331,400	37,837,610
Weighted-average shares outstanding—diluted	39,083,577	39,107,241	39,020,127	39,044,388
Net income per share—basic	$ 0.14	$ 0.12	$ 0.47	$ 0.49
Net income per share—diluted	$ 0.13	$ 0.12	$ 0.46	$ 0.48
Anti-dilutive securities not considered in diluted EPS calculation	451,325		451,325