Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Total revenue	$ 239	$ 112	$ 438	$ 249
Costs and expenses:
Cost of goods sold	135	203	292	378
Research and development	2,031	1,295	3,986	2,328
Selling, general and administrative	1,325	1,582	3,032	3,386
Total costs and expenses	3,491	3,080	7,310	6,092
Operating loss	(3,252)	(2,968)	(6,872)	(5,843)
Other income (expense):
Interest income	35	23	71	23
Other expense, net				(1)
Total other income, net	35	23	71	22
Net loss	$ (3,217)	$ (2,945)	$ (6,801)	$ (5,821)
Net loss per share, basic and diluted (in dollars per share)	$ (0.08)	$ (0.08)	$ (0.18)	$ (0.15)
Weighted-average shares used in computing net loss per share, basic and diluted (in shares)	38,247,288	38,140,232	38,242,728	38,139,063
Product [Member]
Revenue:
Total revenue	$ 89	$ 101	$ 171	$ 210
Collaboration Agreement [Member]
Revenue:
Total revenue	$ 150	$ 11	$ 267	$ 39