Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue:
Product and service	$ 13,910	$ 11,264	$ 37,240	$ 30,278
Collaboration	1,783	1,079	3,112	1,697
Total revenue	15,693	12,343	40,352	31,975
Costs and expenses:
Cost of product and service revenue	6,289	5,271	17,500	14,456
Research and development	5,812	5,961	17,526	15,967
Selling, general and administrative	12,036	12,515	38,984	36,069
Total costs and expenses	24,137	23,747	74,010	66,492
Loss from operations	(8,444)	(11,404)	(33,658)	(34,517)
Other income (expense):
Interest income	58	65	181	204
Interest expense	(1,022)	(697)	(3,007)	(3,248)
Other expense, net	(59)	(112)	(281)	(97)
Total other income (expense), net	(1,023)	(744)	(3,107)	(3,141)
Net loss	$ (9,467)	$ (12,148)	$ (36,765)	$ (37,658)
Net loss per share - basic and diluted	$ (0.49)	$ (0.67)	$ (1.95)	$ (2.13)
Weighted average shares used in computing basic and diluted net loss per share	19,431	18,134	18,862	17,711