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. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Accounting Policies [Abstract]
Net income	$ 4,655	$ 5,014	$ 10,593	$ 22,425
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)	11,241	11,169	11,276	11,141
Dilutive potential common shares (in shares)	245	141	280	120
Diluted weighted-average common shares outstanding (in shares)	11,486	11,310	11,556	11,261
Earnings per share
Basic (in dollars per share)	$ 0.41	$ 0.45	$ 0.94	$ 2.01
Diluted (in dollars per share)	$ 0.41	$ 0.44	$ 0.92	$ 1.99