Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Collaboration revenue	$ 148,090	$ 70,149	$ 235,279	$ 116,303
Operating expenses:
Research and development expenses	40,344	28,205	86,263	53,113
Selling, general and administrative expenses	52,795	41,890	102,530	85,458
Total operating expenses	93,139	70,095	188,793	138,571
Income (loss) from operations	54,951	54	46,486	(22,268)
Other income (expense), net:
Interest expense	(5,336)	(4,982)	(10,566)	(9,870)
Interest income	8	52	17	126
Other income (expense), net	(93)	10	(131)	9
Total other income (expense), net	(5,421)	(4,920)	(10,680)	(9,735)
Income (loss) before income tax expense	49,530	(4,866)	35,806	(32,003)
Income tax expense	(1,611)	(32)	(1,552)	(65)
Net income (loss)	$ 47,919	$ (4,898)	$ 34,254	$ (32,068)
Basic net income (loss) per common share	$ 0.63	$ (0.07)	$ 0.45	$ (0.43)
Diluted net income (loss) per common share	$ 0.60	$ (0.07)	$ 0.43	$ (0.43)
Weighted average common shares used in the calculation of basic net income (loss) per common share	76,577	75,013	76,411	74,919
Weighted average common shares used in the calculation of diluted net income (loss) per common share	80,491	75,013	80,487	74,919