Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2018		252,362,841
Beginning balance at Dec. 31, 2018	$ 735,938	$ 25	$ 1,055,046	$ (66)	$ (319,067)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		7,522,885
Issuance of common stock	7,045		7,044
Stock-based compensation expense	59,064		59,064
Taxes related to net share settlement of restricted stock units	(13,495)		(13,495)
Net loss	(199,876)				(199,876)
Other comprehensive income	298			298
Ending balance (in shares) at Sep. 28, 2019		259,885,726
Ending balance at Sep. 28, 2019	588,974	$ 26	1,107,659	232	(518,943)
Beginning balance (in shares) at Jun. 29, 2019		258,139,452
Beginning balance at Jun. 29, 2019	625,544	$ 25	1,092,306	263	(467,050)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		1,746,274
Issuance of common stock	233	$ 1	232
Stock-based compensation expense	17,971		17,971
Taxes related to net share settlement of restricted stock units	(2,850)		(2,850)
Net loss	(51,893)				(51,893)
Other comprehensive income	(31)			(31)
Ending balance (in shares) at Sep. 28, 2019		259,885,726
Ending balance at Sep. 28, 2019	588,974	$ 26	1,107,659	232	(518,943)
Beginning balance (in shares) at Dec. 31, 2019		264,883,426
Beginning balance at Dec. 31, 2019	487,263	$ 26	1,126,827	188	(639,778)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		7,347,108
Issuance of common stock	2,991	$ 1	2,990
Stock-based compensation expense	55,719		55,719
Taxes related to net share settlement of restricted stock units	(18,816)		(18,816)
Net loss	(138,255)				(138,255)
Other comprehensive income	(10)			(10)
Ending balance (in shares) at Oct. 03, 2020		272,230,534
Ending balance at Oct. 03, 2020	388,892	$ 27	1,166,720	178	(778,033)
Beginning balance (in shares) at Jul. 04, 2020		269,584,380
Beginning balance at Jul. 04, 2020	430,316	$ 27	1,153,520	350	(723,581)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		2,646,154
Issuance of common stock	1,988	$ 0	1,988
Stock-based compensation expense	17,799		17,799
Taxes related to net share settlement of restricted stock units	(6,587)		(6,587)
Net loss	(54,452)				(54,452)
Other comprehensive income	(172)			(172)
Ending balance (in shares) at Oct. 03, 2020		272,230,534
Ending balance at Oct. 03, 2020	$ 388,892	$ 27	$ 1,166,720	$ 178	$ (778,033)