Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Collaboration revenue	$ 260,665	$ 200,478	$ 565,510	$ 435,757
Operating expenses:
Research and development expenses	45,871	45,430	137,841	131,693
Selling, general and administrative expenses	75,809	63,165	234,456	165,695
Total operating expenses	121,680	108,595	372,297	297,388
Income from operations	138,985	91,883	193,213	138,369
Other income (expense), net:
Loss on extinguishment of Convertible Notes	(13,216)		(21,087)
Interest expense	(1,078)	(5,535)	(11,995)	(16,101)
Other, net	159	64	247	(50)
Total other income (expense), net	(14,135)	(5,471)	(32,835)	(16,151)
Income before income tax expense	124,850	86,412	160,378	122,218
Income tax expense	(45,340)	(8,419)	(58,160)	(9,971)
Net income	$ 79,510	$ 77,993	$ 102,218	$ 112,247
Basic net income per common share	$ 0.49	$ 0.51	$ 0.64	$ 0.73
Diluted net income per common share	$ 0.47	$ 0.48	$ 0.62	$ 0.70
Weighted average common shares used in the calculation of basic net income per common share	162,390	154,112	159,198	153,258
Weighted average common shares used in the calculation of diluted net income per common share	168,070	162,446	164,454	161,448