Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenues	$ 5,804	$ 6,478	$ 17,242	$ 21,151
Cost of revenues	1,159	1,798	3,727	5,824
Gross profit	4,645	4,680	13,515	15,327
Operating expenses:
Selling and marketing	1,413	2,541	4,667	7,389
Research and development	2,100	4,174	6,771	12,204
General and administrative	2,220	2,522	6,648	7,878
Restructuring (income) expense	(146)		568
Total operating expenses	5,587	9,237	18,654	27,471
Operating loss	(942)	(4,557)	(5,139)	(12,144)
Other expense:
Change in carrying value of contingent liability		11		668
Loss on related party debt extinguishment	(405)		(405)
Interest (expense) income, net	(315)	(66)	(928)	(68)
Other expense	(2)	(9)	(10)	(26)
Loss before provision for income taxes	(1,664)	(4,621)	(6,482)	(11,570)
Provision for income tax expense	6	11	19	48
Net loss	(1,670)	(4,632)	(6,501)	(11,618)
Other comprehensive income, before tax:
Unrealized holding gains on available-for-sale securities				2
Other comprehensive income, net of tax				2
Comprehensive loss	$ (1,670)	$ (4,632)	$ (6,501)	$ (11,616)
Net loss per share:
Basic and diluted	$ (0.12)	$ (0.38)	$ (0.49)	$ (0.98)
Weighted average shares outstanding:
Basic and diluted	14,297	12,209	13,221	11,826