Net Income (Loss) per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2015	Jun. 28, 2014	Jun. 27, 2015	Jun. 28, 2014
Numerator:
Net income (loss) used in computing basic and diluted net loss per share	$ 838	$ (4,326)	$ 1,621	$ (17,037)
Denominator:
Weighted-average shares used in computing basic net income (loss) per share	58,109	55,812	57,532	55,431
Add potentially dilutive securities	985	0	1,342	0
Weighted-average shares used in computing basic and diluted net income (loss) per share	59,094	55,812	58,874	55,431