CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Product revenue	$ 13,564	$ 7,006
Cost of product revenue	7,330	3,694
Gross profit on product revenue	6,234	3,312
Government contract revenue	3,455	1,428
Operating expenses:
Research and development	9,437	9,150
Selling, general and administrative	13,607	13,683
Total operating expenses	23,044	22,833
Loss from operations	(13,355)	(18,093)
Non-operating expense, net:
Foreign exchange gain (loss)	108	(45)
Interest expense	(915)	(531)
Other income, net	331	106
Total non-operating expense, net	(476)	(470)
Loss before income taxes	(13,831)	(18,563)
Provision for income taxes	54	35
Net loss	$ (13,885)	$ (18,598)
Net loss per share:
Basic	$ (0.11)	$ (0.18)
Diluted	$ (0.11)	$ (0.18)
Weighted average shares outstanding used for calculating net loss per share:
Basic	124,814	103,564
Diluted	124,814	103,564