Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues:
Collaboration agreements	$ 6,110	$ 16,819	$ 21,553
Research grants	4,209	3,986	634
Total revenues	10,319	20,805	22,187
Operating expenses:
Research and development	32,098	33,154	28,984
General and administrative	14,042	12,586	12,605
Total operating expenses	46,140	45,740	41,589
Loss from operations	(35,821)	(24,935)	(19,402)
Interest income, net	71	81	547
Other income			268
Net loss	$ (35,750)	$ (24,854)	$ (18,587)
Basic and diluted net loss per share	$ (0.71)	$ (0.55)	$ (0.44)
Shares used in computing basic and diluted net loss per share	50,512	45,167	42,048