Net Income Per Share - Computation of Basic and Diluted Net Income per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2017	Jun. 29, 2016	Jun. 28, 2017	Jun. 29, 2016
Numerator:
Net income	$ 7,819	$ 7,267	$ 12,696	$ 12,710
Denominator:
Weighted-average shares outstanding—basic (shares)	38,449,240	38,294,575	38,443,130	38,289,505
Weighted-average shares outstanding—diluted (shares)	39,123,961	38,962,802	39,102,501	38,981,610
Net income per share—basic (usd per share)	$ 0.20	$ 0.19	$ 0.33	$ 0.33
Net income per share—diluted (usd per share)	$ 0.20	$ 0.19	$ 0.32	$ 0.33
Anti-dilutive securities not considered in diluted EPS calculation (shares)	763,761	473,836	763,761	473,836