Net Income (Loss) per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 24, 2016	Sep. 26, 2015
Numerator:
Net income (loss)	$ 636	$ 922	$ (15,919)	$ (16,787)
Denominator:
Weighted-average common shares outstanding used to compute basic net income (loss) per share (in shares)	48,773	51,756	48,578	51,814
Effect of dilutive common stock equivalents (in shares)	536	260	0	0
Weighted-average common shares outstanding used to compute diluted net income (loss) per share (in shares)	49,309	52,016	48,578	51,814
Basic net income (loss) per common share (in dollars per share)	$ 0.01	$ 0.02	$ (0.33)	$ (0.32)
Diluted net income (loss) per common share (in dollars per share)	$ 0.01	$ 0.02	$ (0.33)	$ (0.32)
Potentially dilutive shares, weighted average (in shares)	3,951	5,244	5,794	6,062