Subsequent Events	12 Months Ended
Dec. 31, 2011
Subsequent Events [Abstract]
Subsequent Events	27. Subsequent Events *Isis Pharmaceuticals, Inc.* On January 4, 2012, we entered into an exclusive, worldwide option and development agreement with Isis Pharmaceuticals, Inc. (Isis) under which both companies will develop and commercialize Isis’ antisense investigational drug, ISIS-SMN_Rx, for the treatment of spinal muscular atrophy (SMA). Under the terms of the agreement, Isis received an upfront payment of $29.0 million and is eligible to receive up to $45.0 million in milestone payments associated with the clinical development of ISIS-SMN_Rx prior to licensing. Biogen Idec has the option to license ISIS-SMN_Rx until completion of the first successful Phase 2/3 trial. Isis could receive up to another $225.0 million in a license fee and regulatory milestone payments. Isis will be responsible for global development of ISIS-SMN_Rx through the completion of Phase 2/3 trials and we will provide advice on the clinical trial design and regulatory strategy. If we exercise our option, we will assume global development, regulatory and commercialization responsibilities.

Subsequent Events

12 Months Ended

Dec. 31, 2011

27. Subsequent Events

Isis Pharmaceuticals, Inc.

On January 4, 2012, we entered into an exclusive, worldwide option and development agreement with Isis Pharmaceuticals, Inc. (Isis) under which both companies will develop and commercialize Isis’ antisense investigational drug, ISIS-SMN_Rx, for the treatment of spinal muscular atrophy (SMA).

Under the terms of the agreement, Isis received an upfront payment of $29.0 million and is eligible to receive up to $45.0 million in milestone payments associated with the clinical development of ISIS-SMN_Rx prior to licensing. Biogen Idec has the option to license ISIS-SMN_Rx until completion of the first successful Phase 2/3 trial. Isis could receive up to another $225.0 million in a license fee and regulatory milestone payments. Isis will be responsible for global development of ISIS-SMN_Rx through the completion of Phase 2/3 trials and we will provide advice on the clinical trial design and regulatory strategy. If we exercise our option, we will assume global development, regulatory and commercialization responsibilities.