CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenue:
Research and development revenue under collaborative agreements	$ 43,798	$ 23,258	$ 119,975	$ 102,543
Licensing and royalty revenue	265	327	9,325	2,493
Total revenue	44,063	23,585	129,300	105,036
Expenses:
Research, development and patent expenses	61,086	45,660	173,798	126,603
General and administrative	4,470	3,430	13,313	10,241
Total operating expenses	65,556	49,090	187,111	136,844
Loss from operations	(21,493)	(25,505)	(57,811)	(31,808)
Other income (expense):
Investment income	675	434	2,003	1,400
Interest expense	(4,998)	(4,867)	(14,902)	(14,470)
Gain on investments, net	538	175	675	2,073
Loss before income tax (expense) benefit	(25,278)	(29,763)	(70,035)	(42,805)
Income tax (expense) benefit	(1,398)	5,193	(2)	6,437
Net loss	$ (26,676)	$ (24,570)	$ (70,037)	$ (36,368)
Basic and diluted net loss per share (in dollars per share)	$ (0.23)	$ (0.21)	$ (0.60)	$ (0.33)
Shares used in computing basic and diluted net loss per share	117,811	115,263	117,511	108,608