CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Sales	$ 97,926	$ 65,995
Cost of sales	47,665	32,642
Gross profit	50,261	33,353
Operating expenses:
Selling, general and administrative	49,717	34,961
Research and development	14,117	9,389
Total operating expenses	63,834	44,350
Operating loss	(13,573)	(10,997)
Other income (expense), net:
Interest and other income	726	757
Interest and other expense	0	(6)
Change in fair value of common stock warrants	(1,922)	(12,746)
Total other expense, net	(1,196)	(11,995)
Loss before income taxes	(14,769)	(22,992)
Income tax expense	98	0
Net loss	(14,867)	(22,992)
Other comprehensive loss:
Unrealized gain on short-term investments	42	50
Foreign currency translation gain (loss)	(409)	4
Comprehensive loss	$ (15,234)	$ (22,938)
Net loss per share, basic and diluted (in dollars per share)	$ (0.25)	$ (0.40)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	59,740	57,771