Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue, net	$ 1,100	$ 529
Operating expenses:
Cost of goods sold	1,455	1,404
Research and development	1,466	2,182
Sales and marketing	518	851
General and administrative	3,092	1,251
Total operating expenses	6,531	5,688
Loss from operations	(5,431)	(5,159)
Interest expense	189	187
Loss in joint venture	1,419	1,127
Changes in fair value of promissory note	(2,321)	33
Other income, net	(531)	(136)
Loss before tax expense	(4,187)	(6,370)
Tax expense	0	0
Net loss	$ (4,187)	$ (6,370)
Net loss per share - basic and diluted (in usd per share)	$ (0.13)	$ (0.23)
Weighted average common shares outstanding - basic and diluted (in shares)	31,912,170	28,153,555