Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue:
Total revenue	$ 199	$ 137
Costs and expenses:
Cost of goods sold	157	175
Research and development	1,955	1,033
Selling, general and administrative	1,707	1,804
Total costs and expenses	3,819	3,012
Operating loss	(3,620)	(2,875)
Other income (expense):
Interest income	36
Other expense, net		(1)
Total other income (expense), net	36	(1)
Net loss	$ (3,584)	$ (2,876)
Net loss per share, basic and diluted (in dollars per share)	$ (0.09)	$ (0.08)
Weighted-average shares used in computing net loss per share, basic and diluted (in shares)	38,236,056	38,137,881
Product [Member]
Revenue:
Total revenue	$ 82	$ 109
Collaboration Agreement [Member]
Revenue:
Total revenue	$ 117	$ 28