Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding Used to Compute Earnings 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
Accounting Policies [Abstract]
Net income	$ 4,171	$ 4,655	$ 8,362	$ 10,593
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)	11,404	11,241	11,382	11,276
Dilutive potential common shares (in shares)	279	245	257	280
Diluted weighted-average common shares outstanding (in shares)	11,683	11,486	11,639	11,556
Earnings per share
Basic (in dollars per share)	$ 0.37	$ 0.41	$ 0.73	$ 0.94
Diluted (in dollars per share)	$ 0.36	$ 0.41	$ 0.72	$ 0.92