Collaborative and Other Relationships	3 Months Ended
Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative and Other Relationships	Collaborative and Other Relationships Eisai Co., Ltd. On March 4, 2013 we entered into a collaboration with Eisai Co., Ltd. (Eisai) to jointly develop and commercialize two Eisai product candidates for the treatment of Alzheimer’s disease (AD). The agreement also provides Eisai with an option to jointly develop and commercialize two of our candidates for AD, the anti-amyloid beta antibody BIIB037 and an anti-tau monoclonal antibody. The collaboration initially will be centered on the co-development and co-commercialization of Eisai’s two clinical candidates: E2609, a BACE inhibitor, and BAN2401, an anti-amyloid beta antibody. Eisai will serve as the operational and regulatory lead in the co-development of E2609 and BAN2401 and will pursue marketing authorizations for both compounds worldwide. In major markets, such as the U.S. and the E.U., we and Eisai will co-promote the products following marketing approval. Both companies will share overall cost, including research and development expenses and profits will be split between the companies. The agreement excludes commercialization of these candidates in Japan, but includes an option for Eisai to receive an additional one-time payment from us in exchange for expanding joint development and commercialization activities to include Japan. We paid $100.0 million upon closing and recorded approximately $17.7 million reflecting the fair value of the options granted under the agreement, both of which were classified as research and development expense within our condensed consolidated statements of income. We could pay up to approximately an additional $1.0 billion based on the future achievement of certain development, regulatory and commercial milestones. Sangamo BioSciences, Inc. On February 22, 2014, we completed an exclusive worldwide research, development and commercialization collaboration and license agreement with Sangamo BioSciences, Inc. (Sangamo) under which both companies will develop and commercialize product candidates for the treatment of two inherited blood disorders, sickle cell disease and beta-thalassemia. The collaboration is currently in the research stage of development. Under the terms of the agreement, we paid Sangamo an upfront payment of $20.0 million in cash, with additional payments of up to $300.0 million based on the achievement of certain development, regulatory and commercial milestones, plus royalties based on sales. We recorded the $20.0 million upfront payment as research and development expenses. Under this arrangement, Sangamo will be responsible for identifying a product candidate for the treatment of beta-thalassemia and advancing that candidate through a completed Phase 1 human clinical trial, at which point we will assume responsibility for development. We will jointly develop a sickle cell disease candidate through the potential filing of an investigative new drug application, after which we will assume clinical responsibilities. We will lead the global development and commercialization efforts and Sangamo will have the option to assume co-promotion responsibilities in the U.S. Isis Pharmaceuticals, Inc. In January 2012, we entered into an exclusive, worldwide option and collaboration agreement with Isis Pharmaceuticals, Inc. (Isis) under which both companies will develop and commercialize Isis’ product candidate for the treatment of spinal muscular atrophy (SMA). In January 2014, we amended the agreement and agreed to pay the clinical trial costs up to approximately $45.0 million related to the development of ISIS-SMNRx through studies which Isis will be responsible for performing. We will recognize the $45.0 million as research and development expenses as the trial costs are incurred. We are providing input on the clinical trial design and regulatory strategy and have an option to license ISIS-SMNRx until completion of the first successful Phase 2/3 trial. Other Research and Discovery Arrangements Samsung Bioepis In February 2012, we finalized an agreement with Samsung BioLogics Co. Ltd. (Samsung Biologics) that established an entity, Samsung Bioepis, to develop, manufacture and market biosimilar pharmaceuticals. Under the terms of the agreement, Samsung Biologics agreed to contribute 280.5 billion South Korean won (approximately $250.0 million) for an 85 percent stake in Samsung Bioepis and we agreed to contribute approximately 49.5 billion South Korean won (approximately $45.0 million) for a 15 percent ownership interest. Our investment is limited to this contribution as we have no obligation to provide any additional funding. As of March 31, 2014, our ownership interest decreased to approximately 12% as Samsung Bioepis secured additional equity financing from Samsung Biologics and we did not participate in such financing. We maintain an option to purchase additional stock based in Samsung Bioepis that would allow us to increase our ownership percentage up to 49.9 percent. The exercise of this option is within our control and is based on paying for 49.9 percent of the total investment made to Samsung Bioepis in excess of what we have already contributed during the agreement plus interest. As of March 31, 2014 and December 31, 2013, the carrying value of our investment in Samsung Bioepis totaled 18.4 billion and 25.2 billion South Korean won (approximately $17.5 million and $23.9 million), respectively, which is classified as a component of investments and other assets within our condensed consolidated balance sheets. We recognize our share of the results of operations related to our investment in Samsung Bioepis one quarter in arrears when the results of the entity become available, which is reflected as equity in loss of investee, net of tax within our condensed consolidated statements of income. During the three months ended March 31, 2014, we recognized a loss on our investment of $7.6 million, compared to $3.8 million in the prior year comparative period. Simultaneous with the formation of Samsung Bioepis, we entered into a license agreement, a technical development services agreement and a manufacturing agreement with Samsung Bioepis. For the three months ended March 31, 2014, we recognized $24.1 million in other revenues in relation to these services, compared to $6.8 million in the prior year comparative period, which is reflected as a component of other revenues within our condensed consolidated statement of income. On December 17, 2013, pursuant to our joint venture agreement with Samsung Biologics, we exercised our right to enter into an agreement with Samsung Bioepis to commercialize anti-TNF biosimilar product candidates in Europe. Under the terms of this agreement, we paid $36.0 million, which was recorded as a research and development expense within our condensed consolidated statements of income as the programs they relate to had not achieved regulatory approval. Samsung Bioepis is eligible to receive an additional $85.0 million in additional milestones related to clinical development and regulatory approval of the product candidates. Upon commercialization, there will be a 50 percent profit share with Samsung Bioepis. For additional information related to our other significant collaboration arrangements, please read Note 20, Collaborative and Other Relationships to our consolidated financial statements included within our 2013 Form 10-K.

Collaborative and Other Relationships

Eisai Co., Ltd.

On March 4, 2013 we entered into a collaboration with Eisai Co., Ltd. (Eisai) to jointly develop and commercialize two Eisai product candidates for the treatment of Alzheimer’s disease (AD). The agreement also provides Eisai with an option to jointly develop and commercialize two of our candidates for AD, the anti-amyloid beta antibody BIIB037 and an anti-tau monoclonal antibody.

The collaboration initially will be centered on the co-development and co-commercialization of Eisai’s two clinical candidates: E2609, a BACE inhibitor, and BAN2401, an anti-amyloid beta antibody. Eisai will serve as the operational and regulatory lead in the co-development of E2609 and BAN2401 and will pursue marketing authorizations for both compounds worldwide. In major markets, such as the U.S. and the E.U., we and Eisai will co-promote the products following marketing approval. Both companies will share overall cost, including research and development expenses and profits will be split between the companies. The agreement excludes commercialization of these candidates in Japan, but includes an option for Eisai to receive an additional one-time payment from us in exchange for expanding joint development and commercialization activities to include Japan.

We paid $100.0 million upon closing and recorded approximately $17.7 million reflecting the fair value of the options granted under the agreement, both of which were classified as research and development expense within our condensed consolidated statements of income. We could pay up to approximately an additional $1.0 billion based on the future achievement of certain development, regulatory and commercial milestones.

Sangamo BioSciences, Inc.

On February 22, 2014, we completed an exclusive worldwide research, development and commercialization collaboration and license agreement with Sangamo BioSciences, Inc. (Sangamo) under which both companies will develop and commercialize product candidates for the treatment of two inherited blood disorders, sickle cell disease and beta-thalassemia. The collaboration is currently in the research stage of development.

Under the terms of the agreement, we paid Sangamo an upfront payment of $20.0 million in cash, with additional payments of up to $300.0 million based on the achievement of certain development, regulatory and commercial milestones, plus royalties based on sales. We recorded the $20.0 million upfront payment as research and development expenses. Under this arrangement, Sangamo will be responsible for identifying a product candidate for the treatment of beta-thalassemia and advancing that candidate through a completed Phase 1 human clinical trial, at which point we will assume responsibility for development. We will jointly develop a sickle cell disease candidate through the potential filing of an investigative new drug application, after which we will assume clinical responsibilities. We will lead the global development and commercialization efforts and Sangamo will have the option to assume co-promotion responsibilities in the U.S.

Isis Pharmaceuticals, Inc.

In January 2012, we entered into an exclusive, worldwide option and collaboration agreement with Isis Pharmaceuticals, Inc. (Isis) under which both companies will develop and commercialize Isis’ product candidate for the treatment of spinal muscular atrophy (SMA).

In January 2014, we amended the agreement and agreed to pay the clinical trial costs up to approximately $45.0 million related to the development of ISIS-SMNRx through studies which Isis will be responsible for performing. We will recognize the $45.0 million as research and development expenses as the trial costs are incurred. We are providing input on the clinical trial design and regulatory strategy and have an option to license ISIS-SMNRx until completion of the first successful Phase 2/3 trial.

Other Research and Discovery Arrangements

Samsung Bioepis

In February 2012, we finalized an agreement with Samsung BioLogics Co. Ltd. (Samsung Biologics) that established an entity, Samsung Bioepis, to develop, manufacture and market biosimilar pharmaceuticals. Under the terms of the agreement, Samsung Biologics agreed to contribute 280.5 billion South Korean won (approximately $250.0 million) for an 85 percent stake in Samsung Bioepis and we agreed to contribute approximately 49.5 billion South Korean won (approximately $45.0 million) for a 15 percent ownership interest. Our investment is limited to this contribution as we have no obligation to provide any additional funding. As of March 31, 2014, our ownership interest decreased to approximately 12% as Samsung Bioepis secured additional equity financing from Samsung Biologics and we did not participate in such financing. We maintain an option to purchase additional stock based in Samsung Bioepis that would allow us to increase our ownership percentage up to 49.9 percent. The exercise of this option is within our control and is based on paying for 49.9 percent of the total investment made to Samsung Bioepis in excess of what we have already contributed during the agreement plus interest.

As of March 31, 2014 and December 31, 2013, the carrying value of our investment in Samsung Bioepis totaled 18.4 billion and 25.2 billion South Korean won (approximately $17.5 million and $23.9 million), respectively, which is classified as a component of investments and other assets within our condensed consolidated balance sheets. We recognize our share of the results of operations related to our investment in Samsung Bioepis one quarter in arrears when the results of the entity become available, which is reflected as equity in loss of investee, net of tax within our condensed consolidated statements of income. During the three months ended March 31, 2014, we recognized a loss on our investment of $7.6 million, compared to $3.8 million in the prior year comparative period.

Simultaneous with the formation of Samsung Bioepis, we entered into a license agreement, a technical development services agreement and a manufacturing agreement with Samsung Bioepis. For the three months ended March 31, 2014, we recognized $24.1 million in other revenues in relation to these services, compared to $6.8 million in the prior year comparative period, which is reflected as a component of other revenues within our condensed consolidated statement of income.

On December 17, 2013, pursuant to our joint venture agreement with Samsung Biologics, we exercised our right to enter into an agreement with Samsung Bioepis to commercialize anti-TNF biosimilar product candidates in Europe. Under the terms of this agreement, we paid $36.0 million, which was recorded as a research and development expense within our condensed consolidated statements of income as the programs they relate to had not achieved regulatory approval. Samsung Bioepis is eligible to receive an additional $85.0 million in additional milestones related to clinical development and regulatory approval of the product candidates. Upon commercialization, there will be a 50 percent profit share with Samsung Bioepis.

For additional information related to our other significant collaboration arrangements, please read Note 20, Collaborative and Other Relationships to our consolidated financial statements included within our 2013 Form 10-K.