Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Product revenue	$ 3,530	$ 2,182	$ 6,685	$ 2,923
Royalty revenue	609	324	1,151	468
Contract revenue	16	1,537	20	1,553
Total revenue	4,155	4,043	7,856	4,944
Cost of product revenue	2,587	2,074	5,175	3,111
Cost of contract revenue	5	782	6	789
Total cost of revenue	2,592	2,856	5,181	3,900
Gross profit	1,563	1,187	2,675	1,044
Research and development expense	2,879	2,011	5,476	3,909
Sales, marketing, general and administrative expense	2,171	1,946	4,239	3,867
Total operating expenses	5,050	3,957	9,715	7,776
Loss from operations	(3,487)	(2,770)	(7,040)	(6,732)
Other income, net	11	1	8	1
Net loss	$ (3,476)	$ (2,769)	$ (7,032)	$ (6,731)
Net loss per share - basic and diluted	$ (0.07)	$ (0.06)	$ (0.14)	$ (0.15)
Weighted-average shares outstanding - basic and diluted	51,567	46,663	49,566	45,818