Condensed Statements of Operations (Unaudited) (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
Condensed Statements of Operations [Abstract]
Alliance revenue	$ 4	$ 5,089	$ 45	$ 15,052
Operating expenses:
Research and development	3,574	7,786	12,269	19,333
General and administrative	1,948	2,193	6,400	7,709
Total operating expenses	5,522	9,979	18,669	27,042
Loss from operations	(5,518)	(4,890)	(18,624)	(11,990)
Other income (expense):
Investment income, net	2	31	28	86
Foreign currency exchange gain (loss)	27	148	(20)	(46)
Net loss	$ (5,489)	$ (4,711)	$ (18,616)	$ (11,950)
Basic net loss per common share (Note 12)	$ (0.20)	$ (0.18)	$ (0.67)	$ (0.49)
Diluted net loss per common share (Note 12)	$ (0.20)	$ (0.18)	$ (0.67)	$ (0.49)
Shares used in computing basic net loss per common share	27,632	25,980	27,618	24,314
Shares used in computing diluted net loss per common share	27,632	25,980	27,618	24,314