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		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Accounting Policies [Abstract]
Net income	$ 1,591	$ 3,823	$ 4,191	$ 5,938
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)	11,394	11,237	11,370	11,253
Dilutive potential common shares (in shares)	230	254	239	303
Diluted weighted-average common shares outstanding (in shares)	11,624	11,491	11,609	11,556
Earnings per share
Basic (in dollars per share)	$ 0.14	$ 0.34	$ 0.37	$ 0.53
Diluted (in dollars per share)	$ 0.14	$ 0.33	$ 0.36	$ 0.51