Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Contract revenue	$ 13,401	$ 12,804	$ 18,860
License and royalty revenue	418	1,727	2,090
Total revenues	13,819	14,531	20,950
Operating expenses:
Research and development	14,391	10,355	11,061
Manufacturing and production	6,479	6,291	10,927
General and administrative	6,335	7,062	8,366
Total operating expenses	27,205	23,708	30,354
Loss from operations	(13,386)	(9,177)	(9,404)
Other income:
Investment and other income, net	426	204	166
Net loss	$ (12,960)	$ (8,973)	$ (9,238)
Basic and diluted net loss per share	$ (1.01)	$ (0.90)	$ (1.01)
Weighted average shares used in computing basic and diluted net loss per share	12,888	10,019	9,175