Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 23, 2016	Dec. 25, 2015
Statement Of Financial Position [Abstract]
Account receivable, allowance	$ 42	$ 158
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	32,912,546	32,279,429
Common stock, shares outstanding	32,912,546	32,279,429
Treasury stock, shares	601,944	601,944