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. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Accounting Policies [Abstract]
Net income	$ 8,303	$ 4,171	$ 23,590	$ 8,362
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)	11,551	11,404	11,501	11,382
Dilutive potential common shares (in shares)	243	279	283	257
Diluted weighted-average common shares outstanding (in shares)	11,794	11,683	11,784	11,639
Earnings per share
Basic (in dollars per share)	$ 0.72	$ 0.37	$ 2.05	$ 0.73
Diluted (in dollars per share)	$ 0.70	$ 0.36	$ 2.00	$ 0.72