CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenue:
Research and development revenue under collaborative agreements	$ 19,550	$ 41,671
Licensing and royalty revenue	8,611	1,689
Total revenue	28,161	43,360
Expenses:
Research, development and patent expenses	53,448	38,312
General and administrative	4,380	3,423
Total operating expenses	57,828	41,735
Income (loss) from operations	(29,667)	1,625
Other income (expense):
Investment income	657	376
Interest expense	(4,943)	(4,795)
Gain on investments, net	397	1,058
Loss before income tax benefit	(33,556)	(1,736)
Income tax benefit	2,276	64
Net loss	$ (31,280)	$ (1,672)
Basic and diluted net loss per share (in dollars per share)	$ (0.27)	$ (0.02)
Shares used in computing basic net loss per share (in shares)	117,128	101,875