CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenue (including amounts from a related party of $2,456 for the three months ended June 30, 2011 and 2010, and $4,913 for the six months ended June 30, 2011 and 2010)	$ 6,389	$ 6,264	$ 12,719	$ 11,979
Operating expenses:
Research and development	22,798	18,705	43,262	39,057
General and administrative	7,248	6,991	14,417	13,467
Total operating expenses	30,046	25,696	57,679	52,524
Loss from operations	(23,657)	(19,432)	(44,960)	(40,545)
Interest income	118	134	263	229
Interest expense	(1,506)	(1,508)	(3,015)	(3,025)
Net loss	$ (25,045)	$ (20,806)	$ (47,712)	$ (43,341)
Basic and diluted net loss per share (in dollars per share)	$ (0.31)	$ (0.28)	$ (0.59)	$ (0.63)
Shares used in computing net loss per share, basic (in shares)	81,811	73,282	81,415	69,124
Shares used in computing net loss per share, diluted (in shares)	81,811	73,282	81,415	69,124