Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Revenue, net	$ 6,403	$ 6,081
Cost of goods sold	3,358	3,184
Gross margin	3,045	2,897
Operating expense:
Research and development	1,670	2,064
Selling, general and administrative	15,251	11,465
Total operating expense	16,921	13,529
Operating loss	(13,876)	(10,632)
Other income (expense), net:
Interest expense, net	(861)	(939)
Other expense	0	(3)
Other income	53	0
Total other income (expense), net	(808)	(942)
Loss before income taxes	(14,684)	(11,574)
Provision for income taxes	0	0
Net loss	(14,684)	(11,574)
Preferred stock dividend	(550)	(550)
Net loss attributable to common stockholders	$ (15,234)	$ (12,124)
Net loss per share of common shares outstanding - basic and diluted (usd per share)	$ (0.15)	$ (1.72)
Weighted average common shares outstanding - basic and diluted (in shares)	100,301,741	7,042,012