CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 29, 2018		175,452
Beginning balance at Dec. 29, 2018	$ 703,821	$ 175	$ 1,685,916	$ (25,300)	$ (956,970)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
ESPP shares issued (in shares)		1,825
ESPP shares issued	7,740	$ 2	7,738
Restricted stock units released (in shares)		138
Restricted stock units released	0
Stock-based compensation	9,056		9,056
Other comprehensive loss	(5,414)			(5,414)
Net loss	(121,601)				(121,601)
Ending balance (in shares) at Mar. 30, 2019		177,415
Ending balance at Mar. 30, 2019	617,299	$ 177	1,702,710	(30,714)	(1,054,874)
Beginning balance (in shares) at Dec. 28, 2019		181,134
Beginning balance at Dec. 28, 2019	386,535	$ 181	1,740,884	(34,639)	(1,319,891)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
ESPP shares issued (in shares)		1,839
ESPP shares issued	7,394	$ 2	7,392
Restricted stock units released (in shares)		225
Restricted stock units released	0
Stock-based compensation	11,411		11,411
Conversion option related to convertible senior notes, net of allocated costs	67,797		67,797
Other comprehensive loss	(11,500)			(11,500)
Net loss	(99,268)				(99,268)
Ending balance (in shares) at Mar. 28, 2020		183,198
Ending balance at Mar. 28, 2020	$ 361,719	$ 183	$ 1,827,484	$ (46,139)	$ (1,419,809)