Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Sales:
Sales	$ 14,216	$ 7,617	$ 37,939	$ 19,880
Cost of sales:
Cost of sales	6,597	4,151	17,641	10,101
Gross profit	7,619	3,466	20,298	9,779
Operating expenses:
Selling, general and administrative expenses	15,221	11,358	40,814	33,349
Research, development and engineering costs, net	4,385	3,136	11,891	10,730
Total operating expenses	19,606	14,494	52,705	44,079
Operating loss	(11,987)	(11,028)	(32,407)	(34,300)
Interest expense, net	986	422	2,772	1,190
Other expense, net	11	179	88	499
Loss before provision for income taxes	(12,984)	(11,629)	(35,267)	(35,989)
Provision for income taxes	(17)	9	11	9
Net loss	(12,967)	(11,638)	(35,278)	(35,998)
Other comprehensive gain:
Unrealized holding gain on investments arising during period			1	2
Other comprehensive gain			1	2
Comprehensive loss	$ (12,967)	$ (11,638)	$ (35,277)	$ (35,996)
Basic and diluted net loss per share (in dollars per share)	$ (0.87)	$ (1.09)	$ (2.55)	$ (3.43)
Basic and diluted weighted average shares outstanding (in shares)	14,840	10,697	13,852	10,497
Product [Member]
Sales:
Sales	$ 13,813	$ 7,431	$ 36,686	$ 18,684
Cost of sales:
Cost of sales	6,361	4,019	16,577	9,393
Service [Member]
Sales:
Sales	403	186	1,253	1,196
Cost of sales:
Cost of sales	$ 236	$ 132	$ 1,064	$ 708