CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Collaboration revenue	$ 46,154	$ 36,825
Operating expenses:
Research and development expenses	24,908	20,030
Selling, general and administrative expenses	43,568	15,687
Total operating expenses	68,476	35,717
(Loss) income from operations	(22,322)	1,108
Other income (expense), net:
Interest expense	(4,888)	(585)
Interest income	74	27
Other income (expense), net	(1)	(98)
Total other income (expense), net	(4,815)	(656)
Net (loss) income before income tax expense	(27,137)	452
Income tax expense	(33)	(12)
Net (loss) income	$ (27,170)	$ 440
Basic net (loss) income per common share	$ (0.36)	$ 0.01
Diluted net (loss) income per common share	$ (0.36)	$ 0.01
Weighted-average common shares used in the calculation of basic net (loss) income per common share	74,824	71,907
Weighted-average common shares used in the calculation of diluted net (loss) income per common share	74,824	77,299