CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Product revenue	$ 7,006	$ 7,632
Cost of product revenue	3,694	4,263
Gross profit on product revenue	3,312	3,369
Government contracts revenue	1,428
Operating expenses:
Research and development	9,150	6,917
Selling, general and administrative	13,633	11,747
Amortization of intangible assets	50	50
Total operating expenses	22,833	18,714
Loss from operations	(18,093)	(15,345)
Non-operating expense, net:
Foreign exchange loss	(45)	(117)
Interest expense	(531)	(655)
Other income, net	106	66
Total non-operating expense, net	(470)	(706)
Loss before income taxes	(18,563)	(16,051)
Provision for income taxes	35	812
Net loss	$ (18,598)	$ (16,863)
Net loss per share:
Basic	$ (0.18)	$ (0.17)
Diluted	$ (0.18)	$ (0.17)
Weighted average shares outstanding used for calculating net loss per share:
Basic	103,564	99,471
Diluted	103,564	99,471