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. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Schedule Of Computation Of Basic And Diluted Earnings Per Common Share [Line Items]
Net income (loss)	$ 1,230	$ (481)	$ 4,159	$ (10,276)
Weighted-average shares - basic	21,714	20,869	21,475	20,704
Effect of dilutive potential common shares	1,256		1,514
Weighted-average shares - diluted	22,970	20,869	22,989	20,704
Net income (loss) per share - basic	$ 0.06	$ (0.02)	$ 0.19	$ (0.50)
Net income (loss) per share - diluted	$ 0.05	$ (0.02)	$ 0.18	$ (0.50)