Stock Based Compensation - Summary of Stock Options (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017
Number of Options
Outstanding at beginning of period (in shares)	308,888
Granted (in shares)	141,777	0
Exercised (in shares)	0
Canceled/forfeited (in shares)	(169,510)
Outstanding at end of period (in shares)	281,155
Vested or expected to vest (in shares)	263,492
Vested and exercisable (in shares)	104,526
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 27.74
Granted (in dollars per share)	4.65
Exercised (in dollars per share)	0.00
Canceled/forfeited (in dollars per share)	25.32
Outstanding at end of period (in dollars per share)	17.56
Vested or expected to vest (in dollars per share)	18.13
Vested and exercisable (in dollars per share)	$ 32.01
Outstanding, Weighted Average Remaining Contractual Life (years)	7 years 3 months 26 days
Vested or expected to vest, Weighted Average Remaining Contractual Life (years)	7 years 2 months 16 days
Vested and exercisable, Weighted Average Remaining Contractual Life (years)	4 years 5 months 27 days
Outstanding, Aggregate Intrinsic Value	$ 759
Vested and exercisable, Aggregate Intrinsic Value	$ 0