Unaudited Quarterly Results (Details) (USD $)	3 Months Ended												12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 414,602,000	[1]	$ 427,687,000	[1]	$ 304,399,000	[1]	$ 231,789,000	[1]	$ 122,977,000	$ 102,833,000	$ 107,810,000	$ 112,204,000	$ 1,378,477,000	$ 445,824,000	$ 459,074,000
Net income (loss)	470,407,000	[2]	191,468,000	[2]	76,743,000	[2]	11,651,000	[2]	(53,443,000)	(62,365,000)	(62,505,000)	(43,447,000)	750,269,000	(221,760,000)	(104,468,000)
Net income per share - basic (in dollars per share)	$ 4.92		$ 2.02		$ 0.81		$ 0.12						$ 7.92	$ (2.45)	$ (1.26)
Net income per share - diluted (in dollars per share)	$ 4.08		$ 1.72		$ 0.70		$ 0.11						$ 6.75	$ (2.45)	$ (1.26)
Net loss per share - basic and diluted									$ (0.58)	$ (0.68)	$ (0.69)	$ (0.49)
Substantive milestone payment	10,000,000		65,000,000
Income tax benefit	$ (335,800,000)												$ (335,848,000)

[1] Revenues in the third and fourth quarter of 2012 included substantive milestones of $65.0 million and $10.0 million, respectively.

[2] Net income for the quarter ended December 31, 2012 included an income tax benefit of $335.8 million, primarily attributable to the release of substantially all of the Company's valuation allowance against its deferred tax assets.