Computation of Basic and Diluted Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net income (loss)	$ (1,099)	$ 1,230	$ (6,402)	$ 4,159
Weighted-average shares - basic	22,719	21,714	22,429	21,475
Effect of dilutive potential common shares		1,256		1,514
Weighted-average shares - diluted	22,719	22,970	22,429	22,989
Net income (loss) per share - basic	$ (0.05)	$ 0.06	$ (0.29)	$ 0.19
Net income (loss) per share -diluted	$ (0.05)	$ 0.05	$ (0.29)	$ 0.18