Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Earnings Per Share [Abstract]
Basic and diluted net loss	$ (7,275)	$ (19,711)
Shares used in basic and diluted net loss per share (in shares)	121,800	118,833
Basic and diluted Net loss per share (in usd per share)	$ (0.06)	$ (0.17)
Stock options, RSU's and ESPP shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS (in shares)	5,582	8,217