Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss
Revenue	$ 814	$ 19	$ 1,367	$ 19
Cost of sales	1,714	34	2,759	34
Gross profit	(900)	(15)	(1,392)	(15)
Expenses:
Sales and marketing expenses	1,249	635	2,389	1,268
Research and development expenses	5,604	7,539	12,602	13,955
General and administrative expenses	3,888	3,361	7,655	7,241
Operating loss	(11,641)	(11,550)	(24,038)	(22,479)
Other income (expense), net:
Interest income	37	31	58	34
Interest expense	(767)	(268)	(1,451)	(544)
Other expense	(3)	(74)	(16)	(89)
Net loss	(12,374)	(11,861)	(25,447)	(23,078)
Total comprehensive loss	$ (12,374)	$ (11,861)	$ (25,447)	$ (23,078)
Basic and diluted net loss per common share	$ (0.12)	$ (0.13)	$ (0.26)	$ (0.27)
Basic and diluted weighted-average shares outstanding (in shares)	103,689,994	92,742,097	98,825,088	85,033,493