Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenues	$ 6,525	$ 5,804	$ 18,933	$ 17,242
Cost of revenues	979	1,159	3,404	3,727
Gross profit	5,546	4,645	15,529	13,515
Operating expenses:
Selling and marketing	1,311	1,413	4,488	4,667
Research and development	2,049	2,100	6,499	6,771
General and administrative	2,048	2,220	6,299	6,648
Restructuring expense	83	(146)	135	568
Total operating expenses	5,491	5,587	17,421	18,654
Operating income (loss)	55	(942)	(1,892)	(5,139)
Other expense:
Interest expense, net	(128)	(315)	(445)	(928)
Change in fair value of warrant liability	(902)		(3,126)
Loss on debt extinguishment		(405)		(405)
Other expense	(1)	(2)	(48)	(10)
Loss before provision for income taxes	(976)	(1,664)	(5,511)	(6,482)
Provision for income tax expense	7	6	30	19
Net loss	$ (983)	$ (1,670)	$ (5,541)	$ (6,501)
Net loss per share:
Basic and diluted	$ (0.04)	$ (0.12)	$ (0.28)	$ (0.49)
Weighted average shares outstanding:
Basic and diluted	25,020	14,297	20,771	13,221
Preferred dividends per share	$ 31.58		$ 105.54