Fair Value Measurements (Details 3) (USD $)	3 Months Ended								12 Months Ended				1 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	Dec. 31, 2012 Convertible senior notes due 2016	Sep. 30, 2012 Proteolix	Apr. 30, 2010 Proteolix	Dec. 31, 2012 Proteolix	Dec. 31, 2011 Proteolix	Dec. 31, 2010 Proteolix
Summary of the changes in the fair value of the non-current liability for contingent consideration:
Fair value at beginning of period															$ 159,990,000	$ 253,458,000	$ 200,528,000
Payments													(80,000,000)	(40,000,000)
Change in valuation	(2,937,000)	(9,843,000)	(53,214,000)	(3,178,000)	116,663,000	(5,945,000)	(5,755,000)	(11,495,000)	(69,173,000)	93,468,000	(92,930,000)				(69,173,000)	93,468,000	(92,930,000)
Fair value at end of period															149,163,000	159,990,000	253,458,000
Estimated fair value of senior notes												$ 468,500,000