Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Collaboration revenue	$ 175,657	$ 148,090	$ 304,845	$ 235,279
Operating expenses:
Research and development expenses	47,294	40,344	91,970	86,263
Selling, general and administrative expenses	74,708	52,795	158,647	102,530
Total operating expenses	122,002	93,139	250,617	188,793
Income from operations	53,655	54,951	54,228	46,486
Other income (expense), net:
Loss on extinguishment of Convertible Notes	(7,868)		(7,871)
Interest expense	(5,309)	(5,336)	(10,917)	(10,566)
Interest income	30	8	41	17
Other, net	(82)	(93)	47	(131)
Total other income (expense), net	(13,229)	(5,421)	(18,700)	(10,680)
Income before income tax expense	40,426	49,530	35,528	35,806
Income tax expense	(14,600)	(1,611)	(12,820)	(1,552)
Net income	$ 25,826	$ 47,919	$ 22,708	$ 34,254
Basic net income per common share	$ 0.33	$ 0.63	$ 0.29	$ 0.45
Diluted net income per common share	$ 0.31	$ 0.60	$ 0.28	$ 0.43
Weighted average common shares used in the calculation of basic net income per common share	79,252	76,577	78,788	76,411
Weighted average common shares used in the calculation of diluted net income per common share	84,345	80,491	81,498	80,487