Net Loss per Share - Antidilutive Securities (Details) - 2015 Employee Stock Purchase Plan - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2020	Jun. 29, 2019	Jul. 04, 2020	Jun. 29, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	34,394	37,890	34,394	39,592
Stock options to purchase common stock | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	11,927	15,594	11,927	15,684
RSUs | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	22,237	20,712	22,237	22,357
Warrant | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	230	230	230	230
Diluted impact of Employee Stock Purchase Plan | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	0	1,354	0	1,321