Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Collaboration agreements	$ 7,801	$ 9,721	$ 20,472	$ 17,289
Research grants	557	664	1,377	1,212
Total revenues	8,358	10,385	21,849	18,501
Operating expenses:
Research and development	15,618	13,460	30,598	25,543
General and administrative	5,017	3,972	9,749	7,616
Total operating expenses	20,635	17,432	40,347	33,159
Loss from operations	(12,277)	(7,047)	(18,498)	(14,658)
Interest and other income, net	151	66	305	105
Loss before income taxes	(12,126)	(6,981)	(18,193)	(14,553)
Benefit from income taxes			748
Net loss	$ (12,126)	$ (6,981)	$ (17,445)	$ (14,553)
Basic and diluted net loss per share	$ (0.17)	$ (0.10)	$ (0.25)	$ (0.22)
Shares used in computing basic and diluted net loss per share	69,684	67,980	69,485	65,603