Consolidated Statements of Operations - 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]
Product revenue	$ 2,298	$ 3,617	$ 2,298	$ 10,302
Royalty revenue	359	331	1,240	1,482
Contract revenue	3,429	52	4,793	72
Total revenue	6,086	4,000	8,331	11,856
Cost of product revenue	3,224	2,767	3,572	7,942
Cost of contract revenue	2,619	26	3,754	32
Total cost of revenue	5,843	2,793	7,326	7,974
Gross profit	243	1,207	1,005	3,882
Research and development expense	3,427	3,053	10,417	8,529
Sales, marketing, general and administrative expense	2,062	2,231	6,967	6,470
Total operating expenses	5,489	5,284	17,384	14,999
Loss from operations	(5,246)	(4,077)	(16,379)	(11,117)
Other (expense) income, net	5	7	(3)	15
Net loss	$ (5,241)	$ (4,070)	$ (16,382)	$ (11,102)
Net loss per share - basic and diluted	$ (0.07)	$ (0.08)	$ (0.23)	$ (0.22)
Weighted-average shares outstanding - basic and diluted	74,922	52,111	70,828	50,421