Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income (loss)	$ 6,974	$ (43,052)	$ (19,201)	$ (63,349)
Shares used in basic Net income (loss) per share (in shares)	127,816	122,990	125,578	122,393
Dilutive effect of stock options, RSUs and ESPP shares (in shares)	1,658	0	0	0
Shares used in diluted Net income (loss) per share (in shares)	129,474	122,990	125,578	122,393
Basic Net income (loss) per share (in usd per share)	$ 0.05	$ (0.35)	$ (0.15)	$ (0.52)
Diluted Net income (loss) per share (in usd per share)	$ 0.05	$ (0.35)	$ (0.15)	$ (0.52)
Stock options, RSUs, and ESPP shares excluded as they are antidilutive (in shares)	2,299	7,221	8,284	6,018