CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenue (including amounts from a related party of $2,380 and $2,456 for the three months ended September 30, 2011 and 2010, respectively, and $7,294 and $7,370 for the nine months ended September 30, 2011 and 2010, respectively)	$ 6,431	$ 5,302	$ 19,150	$ 17,281
Operating expenses:
Research and development	27,837	18,537	71,099	57,594
General and administrative	7,796	6,610	22,213	20,077
Total operating expenses	35,633	25,147	93,312	77,671
Loss from operations	(29,202)	(19,845)	(74,162)	(60,390)
Interest income	81	136	344	364
Interest expense	(1,505)	(1,513)	(4,519)	(4,537)
Net loss	$ (30,626)	$ (21,222)	$ (78,337)	$ (64,563)
Basic and diluted net loss per share (in dollars per share)	$ (0.37)	$ (0.29)	$ (0.96)	$ (0.91)
Shares used in computing net loss per share, basic (in shares)	82,490	73,726	81,777	70,675
Shares used in computing net loss per share, diluted (in shares)	82,490	73,726	81,777	70,675