Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 30, 2017
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts, accounts receivable	$ 631	$ 358
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares issued	31,604,459	27,077,145
Common stock, shares outstanding	31,604,459	27,077,145