Condensed Statements of Operations (Unaudited) (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
Condensed Statements of Operations [Abstract]
Alliance revenue	$ 33	$ 4,386	$ 41	$ 9,963
Operating expenses:
Research and development	4,142	6,961	8,695	11,547
General and administrative	2,166	2,784	4,452	5,516
Total operating expenses	6,308	9,745	13,147	17,063
Loss from operations	(6,275)	(5,359)	(13,106)	(7,100)
Other income (expense):
Investment income, net	5	29	26	55
Foreign currency exchange (loss) gain	(12)	34	(47)	(194)
Net loss	$ (6,282)	$ (5,296)	$ (13,127)	$ (7,239)
Basic net loss per common share (Note 12)	$ (0.23)	$ (0.23)	$ (0.48)	$ (0.31)
Diluted net loss per common share (Note 12)	$ (0.23)	$ (0.23)	$ (0.48)	$ (0.31)
Shares used in computing basic net loss per common share	27,619	23,473	27,612	23,467
Shares used in computing diluted net loss per common share	27,619	23,473	27,612	23,467