Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Total revenue	$ 84	$ 130	$ 522	$ 379
Costs and expenses:
Cost of goods sold	109	147	401	525
Research and development	2,262	1,700	6,248	4,028
Selling, general and administrative	1,283	1,322	4,315	4,708
Total costs and expenses	3,654	3,169	10,964	9,261
Operating loss	(3,570)	(3,039)	(10,442)	(8,882)
Other income (expense):
Interest income	29	35	100	58
Other expense, net	(3)	3	(3)	2
Total other income, net	26	38	97	60
Net loss	$ (3,544)	$ (3,001)	$ (10,345)	$ (8,822)
Net loss per share, basic and diluted (in dollars per share)	$ (0.09)	$ (0.08)	$ (0.27)	$ (0.23)
Weighted-average shares used in computing net loss per share, basic and diluted (in shares)	38,277,908	38,146,751	38,254,583	38,141,654
Product [Member]
Revenue:
Total revenue	$ 52	$ 88	$ 223	$ 298
Collaboration Agreement [Member]
Revenue:
Total revenue	$ 32	$ 42	$ 299	$ 81