Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Allowances for doubtful accounts	$ 74	$ 73
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	3,000,000	3,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	47,000,000	47,000,000
Common stock, shares issued	25,227,935	25,070,889
Common stock, shares outstanding	25,227,935	25,070,889