Investments in Variable Interest Entities (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Knopp [Member]	Sep. 30, 2011 Knopp [Member]	Sep. 30, 2012 Knopp [Member]	Sep. 30, 2011 Knopp [Member]	Sep. 30, 2012 Neurimmune [Member]	Sep. 30, 2011 Neurimmune [Member]	Sep. 30, 2012 Neurimmune [Member]	Sep. 30, 2011 Neurimmune [Member]	Dec. 31, 2010 Common Class B [Member] Knopp [Member]
Investment in Variable Interest Entities (Textual) [Abstract]
Purchase of common shares in variable interest entities														30.00%
Remaining potential development milestone payments and royalties on commercial sales under the terms of collaboration agreement								$ 255,000,000				$ 345,000,000
Percentage of funding for R&D cost required in support of the collaboration agreement								100.00%				100.00%
Research and development expense	304,217,000	301,391,000	989,738,000	880,668,000		15,700,000	21,800,000	58,900,000	36,500,000	3,400,000	1,500,000	8,500,000	6,300,000
Payment recognized as a charge to noncontrolling interests, net of tax									10,000,000				15,000,000
Investment in biotechnology companies that are determined to be unconsolidated variable interest entities	$ 9,300,000		$ 9,300,000		$ 14,600,000