Net Income (Loss) per Share - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	29,183	8,117	31,262	7,432
Redeemable convertible preferred stock and stock options to purchase common stock [Member] | Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	19,074	3,861	20,924	3,548
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	9,929	4,256	10,066	3,884
Diluted Impact of ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	70	0	152	0
Diluted Common Stock Subject to Vesting [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	110	0	120	0