Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 29, 2019	Dec. 28, 2018
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 380	$ 600
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
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	90,000,000	90,000,000
Common stock, shares issued	39,061,000	38,881,000
Common stock, shares outstanding	38,171,000	37,991,000
Treasury stock, shares	890	890