CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenue:
Research and development revenue under collaborative agreements	$ 41,921	$ 21,818
Licensing and royalty revenue	1,439	1,417
Total revenue	43,360	23,235
Expenses:
Research and development	38,312	38,714
General and administrative	3,423	2,976
Total operating expenses	41,735	41,690
Income (loss) from operations	1,625	(18,455)
Other income (expense):
Equity in net loss of Regulus Therapeutics Inc.		(976)
Investment income	376	600
Interest expense	(4,795)	(5,179)
Gain on investments, net	1,058	17
Loss before income tax benefit (expense)	(1,736)	(23,993)
Income tax benefit (expense)	64	(2)
Net loss	$ (1,672)	$ (23,995)
Basic and diluted net loss per share (in dollars per share)	$ (0.02)	$ (0.24)
Shares used in computing basic net loss per share (in shares)	101,875	100,157
Shares used in computing diluted net loss per share (in shares)	101,875	100,157