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:
Research and development revenue under collaborative agreements	$ 24,305	$ 21,143	$ 44,319	$ 49,699
Licensing and royalty revenue	518	2,360	1,651	3,730
Total revenue	24,823	23,503	45,970	53,429
Expenses:
Research and development	36,009	39,124	70,254	71,111
General and administrative	2,874	3,051	5,884	5,869
Total operating expenses	38,883	42,175	76,138	76,980
Loss from operations	(14,060)	(18,672)	(30,168)	(23,551)
Other income (expense):
Equity in net loss of Regulus Therapeutics Inc.	(1,033)	(3,942)	(1,889)	(5,428)
Investment income	616	859	1,321	1,814
Interest expense	(3,437)	(3,261)	(6,851)	(6,498)
Gain (loss) on investments, net	34	(136)	(285)	(1,146)
Loss before income tax expense	(17,880)	(25,152)	(37,872)	(34,809)
Income tax expense	(9)	(2)	(11)	(2)
Net loss	$ (17,889)	$ (25,154)	$ (37,883)	$ (34,811)
Basic net loss (in dollars per share)	$ (0.18)	$ (0.25)	$ (0.38)	$ (0.35)
Diluted net loss (in dollars per share)	$ (0.18)	$ (0.25)	$ (0.38)	$ (0.35)
Shares used in computing basic net loss per share (in shares)	99,602	99,091	99,586	99,052
Shares used in computing diluted net loss per share (in shares)	99,602	99,091	99,586	99,052