Condensed Consolidated Statements of Loss and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Collaboration revenue	$ 629	$ 368	$ 1,247	$ 2,097
Product sales	1,246	1,116	1,333	1,553
Total revenue	1,875	1,484	2,580	3,650
Operating expenses:
Cost of goods sold	4,132	4,903	10,279	8,694
Research and development	3,761	4,032	7,585	7,162
General and administrative	3,423	3,898	7,160	7,946
Total operating expenses	11,316	12,833	25,024	23,802
Loss from operations	(9,441)	(11,349)	(22,444)	(20,152)
(Loss)/gain on change in fair value of contingent consideration liability	(801)	7,599	14,032	6,449
Interest and other income/ (expense), net	(10)	2	(15)	8
Interest expense	(2,198)	(2,214)	(4,427)	(3,002)
Net loss	$ (12,450)	$ (5,962)	$ (12,854)	$ (16,697)
Basic and diluted net loss per share	$ (0.63)	$ (0.34)	$ (0.65)	$ (0.96)
Shares used to compute basic and diluted net loss per share	19,775	17,331	19,763	17,307
Other Comprehensive Loss
Change in unrealized gain/(loss) on marketable securities	$ 1	$ 2	$ 3	$ 1
Comprehensive loss	$ (12,449)	$ (5,960)	$ (12,851)	$ (16,696)