CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Product revenue	$ 10,175	$ 8,045	$ 27,058	$ 24,567
Cost of product revenue	5,451	5,560	14,690	17,302
Gross profit on product revenue	4,724	2,485	12,368	7,265
Government contracts revenue	261		261
Operating expenses:
Research and development	7,033	7,689	22,507	18,483
Selling, general and administrative	12,161	10,932	36,314	34,713
Amortization of intangible assets	50	50	151	151
Total operating expenses	19,244	18,671	58,972	53,347
Loss from operations	(14,259)	(16,186)	(46,343)	(46,082)
Non-operating (expense) income, net:
Gain from revaluation of warrant liability		1,109		4,698
Foreign exchange loss	(61)	(10)	(77)	(624)
Interest expense	(586)	(505)	(1,899)	(1,061)
Other income, net	114	7	293	36
Total non-operating (expense) income, net	(533)	601	(1,683)	3,049
Loss before income taxes	(14,792)	(15,585)	(48,026)	(43,033)
(Benefit) provision for income taxes	(416)	95	1,379	(1,921)
Net loss	$ (14,376)	$ (15,680)	$ (49,405)	$ (41,112)
Net loss per share:
Basic	$ (0.14)	$ (0.16)	$ (0.49)	$ (0.43)
Diluted	$ (0.14)	$ (0.17)	$ (0.49)	$ (0.48)
Weighted average shares outstanding used for calculating net loss per share:
Basic	102,769	96,864	101,273	95,347
Diluted	102,769	97,605	101,273	96,340