Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net revenue	$ 15,213	$ 1,488	$ 41,509	$ 2,565
Cost of goods sold	8,463	772	18,358	1,320
Gross profit	6,750	716	23,151	1,245
Operating Expenses
Research and development	6,398	4,874	13,282	9,093
General and administrative	5,537	4,362	13,190	8,377
Sales and marketing	14,220	10,750	30,789	16,664
Total operating expenses	26,155	19,986	57,261	34,134
Loss from operations	(19,405)	(19,270)	(34,110)	(32,889)
Other Income (Expense)
Interest income	65	839	707	1,873
Interest and other expense	(443)	(629)	(995)	(1,161)
Other income (expense), net	(378)	210	(288)	712
Loss before income tax expense	(19,783)	(19,060)	(34,398)	(32,177)
Income tax expense	0	1	1	1
Net loss	(19,783)	(19,061)	(34,399)	(32,178)
Foreign currency translation adjustment	(108)	(43)	(285)	(53)
Comprehensive loss	$ (19,891)	$ (19,104)	$ (34,684)	$ (32,231)
Net loss per share, basic and diluted (USD per share)	$ (0.54)	$ (0.68)	$ (0.98)	$ (1.15)
Weighted-average shares used to compute basic and diluted net loss per share (shares)	36,440,846	27,945,393	35,040,180	27,887,121