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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Investments in Variable Interest Entities (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		1 Months Ended	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Sep. 30, 2011 Neurimmune [Member]	Sep. 30, 2010 Neurimmune [Member]	Sep. 30, 2011 Neurimmune [Member]	Sep. 30, 2010 Neurimmune [Member]	Aug. 31, 2010 Knopp [Member]	Sep. 30, 2011 Knopp [Member]	Mar. 31, 2011 Knopp [Member]	Sep. 30, 2010 Knopp [Member]	Sep. 30, 2011 Knopp [Member]	Sep. 30, 2010 Knopp [Member]
Investment in Variable Interest Entities (Textuals) [Abstract]
Total upfront and reimbursement payment made to collaborative partner										$ 26,400,000			$ 26,400,000		$ 26,400,000
Remaining potential development milestone payments and royalties on commercial sales under the terms of collaboration agreement								345,000,000		265,000,000
Purchase of Class B Common Shares in Variable Interest Entities										30.00%
Purchase Consideration for Variable Interest Entities										60,000,000
IPR&D charge recorded related to collaboration agreement	301,391,000	319,054,000	880,668,000	957,759,000									205,000,000		205,000,000
IPR&D charge allocated to noncontrolling interest													145,000,000		145,000,000
Payment recognized as a charge to noncontrolling interests, net of tax								15,000,000				10,000,000
Biogen Idec's share of research and development expense reflected within our research and development expense						1,500,000	2,400,000	6,300,000	12,800,000		21,800,000			36,500,000
Development expense incurred													1,000,000		1,000,000
Percentage of funding for R&D cost required in support of the collaboration agreement								100.00%
Investment in biotechnology companies that are determined to be unconsolidated variable interest entities	$ 18,100,000		$ 18,100,000		$ 22,900,000
Percentage of operations of joint venture investments on financial statements			100.00%
Percentage of net income (loss) attributable to noncontrolling interests			50.00%