Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue:
Product and service	$ 12,498	$ 10,263	$ 23,330	$ 19,014
Collaboration	568	618	1,329	618
Total revenue	13,066	10,881	24,659	19,632
Costs and expenses:
Cost of product and service revenue	5,871	4,860	11,211	9,185
Research and development	5,798	5,274	11,714	10,006
Selling, general and administrative	12,823	12,880	26,948	23,554
Total costs and expenses	24,492	23,014	49,873	42,745
Loss from operations	(11,426)	(12,133)	(25,214)	(23,113)
Other income (expense):
Interest income	56	75	123	139
Interest expense	(1,001)	(2,015)	(1,985)	(2,551)
Other income (expense)	(33)	(15)	(222)	15
Total other income (expense), net	(978)	(1,955)	(2,084)	(2,397)
Net loss	$ (12,404)	$ (14,088)	$ (27,298)	$ (25,510)
Net loss per share - basic and diluted	$ (0.66)	$ (0.78)	$ (1.47)	$ (1.46)
Weighted average shares used in computing basic and diluted net loss per share	18,831	18,069	18,572	17,496