Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Income Statement [Abstract]
Net revenues	$ 91,961	$ 26,277	$ 199,418	$ 56,420
Cost of goods sold	59,178	21,235	133,123	46,709
Gross profit	32,783	5,042	66,295	9,711
Research and development expenses	5,951	2,165	14,661	6,267
Selling, general and administrative expenses	20,944	10,353	47,636	23,133
Restructuring expenses	2,319	528	3,560	1,170
Total operating expenses	29,214	13,046	65,857	30,570
Income (loss) from operations	3,569	(8,004)	438	(20,859)
Other income (expense), net:
Interest expense	(855)	(313)	(2,329)	(388)
Remeasurement of warrant liability	0	(994)	(12,503)	(1,253)
Other income (expense), net	1,385	(31)	2,424	66
Total other income (expense), net	530	(1,338)	(12,408)	(1,575)
Income (loss) before taxes	4,099	(9,342)	(11,970)	(22,434)
Income tax expense	0	0	21	0
Net income (loss)	$ 4,099	$ (9,342)	$ (11,991)	$ (22,434)
Net income (loss) per share available to common stockholders—basic (in dollars per share)	$ 0.07	$ (1.45)	$ (0.33)	$ (3.68)
Weighted average common shares outstanding—basic	60,415,866	6,441,838	35,806,520	6,103,756
Net income (loss) per share available to common stockholders—diluted (in dollars per share)	$ 0.06	$ (1.45)	$ (0.33)	$ (3.68)
Weighted average common shares outstanding—diluted	66,026,490	6,441,838	35,806,520	6,103,756