CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Product revenue	$ 37,183,000	$ 34,223,000	$ 36,416,000
Cost of product revenue	20,295,000	23,464,000	21,188,000
Gross profit on product revenue	16,888,000	10,759,000	15,228,000
Government contracts revenue	2,092,000
Operating expenses:
Research and development	31,322,000	25,643,000	21,800,000
Selling, general and administrative	48,753,000	45,989,000	37,729,000
Amortization of intangible assets	202,000	202,000	202,000
Impairment of long-lived assets	150,000	0	0
Total operating expenses	80,427,000	71,834,000	59,731,000
Loss from operations	(61,447,000)	(61,075,000)	(44,503,000)
Non-operating (expense) income, net:
Gain from revaluation of warrant liability		3,566,000	7,708,000
Foreign exchange gain (loss)	21,000	(396,000)	(1,296,000)
Interest expense	(2,445,000)	(1,705,000)	(599,000)
Other income, net	1,140,000	71,000	130,000
Total non-operating (expense) income, net	(1,284,000)	1,536,000	5,943,000
Loss before income taxes	(62,731,000)	(59,539,000)	(38,560,000)
Provision (benefit) for income taxes	175,000	(3,671,000)	195,000
Net loss	$ (62,906,000)	$ (55,868,000)	$ (38,755,000)
Net loss per share:
Basic	$ (0.62)	$ (0.58)	$ (0.52)
Diluted	$ (0.62)	$ (0.61)	$ (0.61)
Weighted average shares outstanding used for calculating net loss per share:
Basic	101,826	96,068	74,767
Diluted	101,826	96,905	76,534