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								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Net Income	$ 9,484	$ 4,655	$ 3,823	$ 2,115	$ 2,836	$ 5,014	$ 3,861	$ 13,550	$ 20,077	$ 25,261	$ (74,879)
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)									11,290	11,151	11,047
Dilutive potential common shares (in shares)									268	148	0
Diluted weighted-average common shares outstanding (in shares)									11,558	11,299	11,047
Earnings (Loss) Per Share
Basic (in dollars per share)	$ 0.84	$ 0.41	$ 0.34	$ 0.19	$ 0.25	$ 0.45	$ 0.35	$ 1.22	$ 1.78	$ 2.27	$ (6.78)
Diluted (in dollars per share)	$ 0.82	$ 0.41	$ 0.33	$ 0.18	$ 0.25	$ 0.44	$ 0.34	$ 1.21	$ 1.74	$ 2.24	$ (6.78)