Litigation	9 Months Ended
Sep. 30, 2013
Loss Contingency, Information about Litigation Matters [Abstract]
Litigation	Litigation Massachusetts Department of Revenue On June 8, 2010, we received Notices of Assessment from the Massachusetts DOR against BIMA for the payment of additional corporate excise tax, including associated interest and penalties, related to our 2004, 2005 and 2006 state tax filings. On February 3, 2011, we filed a petition with the Massachusetts ATB appealing the denial of our application for abatement, and on October 15, 2013 we reached a settlement resolving the dispute. Hoechst — Genentech Arbitration On October 24, 2008, Hoechst GmbH (Hoechst), an affiliate of Sanofi-Aventis Deutschland GmbH (Sanofi), filed a request for arbitration with the ICC International Court of Arbitration (Paris) claiming that Genentech breached a license agreement, now terminated, under which Hoechst claims rights (the Hoechst License). The Hoechst License granted Genentech certain rights with respect to U.S. Patents 5,849,522 (’522 patent) and 6,218,140 (’140 patent). In 2012, the arbitrator ruled that Genentech is liable to Hoechst for license royalties with respect to sales of RITUXAN, and in February 2013 he awarded Hoechst royalties of EUR108 million together with interest (estimated by Hoechst to be approximately EUR54 million as of the date of the award). Genentech has filed Declarations of Appeal in the Paris Court of Appeal to vacate the arbitral awards in their entirety and those annulment proceedings are pending. Genentech nonetheless paid Hoechst the amounts that Hoechst claims that it is owed, while reserving all legal rights, including the right to challenge the awards and the right to claim reimbursement. Although we are not a party to the arbitration, we expect that amounts paid by Genentech and not ultimately recovered from Hoechst may be a cost charged to our collaboration with Genentech. Our revenues from unconsolidated joint business were reduced by approximately $50.0 million in the second quarter of 2011 and by approximately $41.5 million in the first quarter of 2013 to reflect our share of the royalties awarded to Hoechst and the interest Hoechst claims. Our share may vary from these amounts if Genentech is successful in challenging the awards. Sanofi ’522 and ’140 Patent Litigation On October 27, 2008, Sanofi filed suit against Genentech and Biogen Idec in the United States District Court for the Eastern District of Texas claiming that RITUXAN infringes the ’522 patent and the ’140 patent. That action was transferred and consolidated with an action filed on the same day by Genentech and Biogen Idec against Sanofi in the United States District for the Northern District of California seeking declaratory judgments that RITUXAN does not infringe the patents and that the asserted patent claims are invalid and unenforceable. On April 21, 2011, the federal court in California entered a separate and final judgment of non-infringement, and the United States Court of Appeals for the Federal Circuit affirmed on March 22, 2012. The federal court in California has stayed further proceedings relating to Biogen Idec's and Genentech's claims for a declaration that the asserted patent claims are invalid and unenforceable, and no trial date has been set on those claims. ’755 Patent Litigation On September 15, 2009, we were issued U.S. Patent No. 7,588,755 (’755 Patent), which claims the use of interferon beta for immunomodulation or treating a viral condition, viral disease, cancers or tumors. This patent, which expires in September 2026, covers, among other things, the treatment of MS with our product AVONEX. On May 27, 2010, Bayer Healthcare Pharmaceuticals Inc. (Bayer) filed a lawsuit against us in the U.S. District Court for the District of New Jersey seeking a declaratory judgment of patent invalidity and non-infringement and seeking monetary relief in the form of attorneys' fees, costs and expenses. On May 28, 2010, BIMA filed a lawsuit in the U.S. District Court for the District of New Jersey alleging infringement of the ’755 Patent by EMD Serono, Inc. (manufacturer, marketer and seller of REBIF), Pfizer, Inc. (co-marketer of REBIF), Bayer (manufacturer, marketer and seller of BETASERON and manufacturer of EXTAVIA), and Novartis Pharmaceuticals Corp. (marketer and seller of EXTAVIA) and seeking monetary damages, including lost profits and royalties. The court has consolidated the two lawsuits, and we refer to the two actions as the “Consolidated ’755 Patent Actions”. Bayer, Pfizer, Novartis and EMD Serono have all filed counterclaims in the Consolidated ’755 Patent Actions seeking declaratory judgments of patent invalidity and non-infringement, and seeking monetary relief in the form of costs and attorneys' fees, and EMD Serono and Bayer have each filed a counterclaim seeking a declaratory judgment that the ’755 Patent is unenforceable based on alleged inequitable conduct. Bayer has also amended its complaint to seek such a declaration. No trial date has been set. Novartis V&D ’688 Patent Litigation On January 26, 2011, Novartis Vaccines and Diagnostics, Inc. (Novartis V&D) filed suit against us in the United States District Court for the District of Delaware, alleging that TYSABRI infringes U.S. Patent No. 5,688,688 “Vector for Expression of a Polypeptide in a Mammalian Cell” (’688 Patent), which was granted in November 1997 and expires in November 2014. Novartis V&D seeks a declaration of infringement, a finding of willful infringement, compensatory damages in the form of a royalty and lost profits, treble damages, interest, costs and attorneys' fees. On July 18, 2012, the court granted Novartis V&D leave to add Novartis Pharma AG, an alleged exclusive licensee of the ’688 Patent, as co-plaintiff. We have not formed an opinion that an unfavorable outcome is either “probable” or “remote”, and are unable to estimate the magnitude or range of any potential loss. We believe that we have good and valid defenses to the complaint and will vigorously defend against it. A trial on liability has been set for January 2014. Italian National Medicines Agency In the fourth quarter of 2011, Biogen Idec SRL received a notice from the Italian National Medicines Agency (Agenzia Italiana del Farmaco or AIFA) stating that sales of TYSABRI for the period from February 2009 through February 2011 exceeded by EUR30.7 million a reimbursement limit established pursuant to a Price Determination Resolution (Price Resolution) granted by AIFA in December 2006. The Price Resolution set the initial price for the sale of TYSABRI in Italy and limited the amount of government reimbursement “for the first 24 months” of TYSABRI sales. As the basis for the claim, the AIFA notice referred to a 2001 Decree that provides for an automatic 24-month renewal of the terms of all Price Resolutions that are not renegotiated prior to the expiration of their term. On November 17, 2011, Biogen Idec SRL responded to AIFA that the reimbursement limit in the Price Resolution by its terms applied only to the first 24 months of TYSABRI sales, which began in February 2007. On December 23, 2011, we filed an appeal in the Regional Administrative Tribunal of Lazio (Il Tribunale Amministrativo Regionale per il Lazio) in Rome against AIFA, seeking a ruling that our interpretation of the Price Resolution is valid and that the position of AIFA is unenforceable, and the appeal is pending. On November 21, 2012, the tribunal ruled that the reimbursement limit would not automatically renew for another 24-month term pending resolution of the dispute. In June 2013, the Price and Reimbursement Committee of AIFA informed Biogen Idec SRL that sales of TYSABRI for February 2011 through February 2013 exceeded the reimbursement limit in the Price Resolution. We dispute that the reimbursement limit applies to this period for the same reason that we dispute its application to the February 2009 through February 2011 period. In July 2013, we reached an agreement in principle with the Price and Reimbursement Committee of AIFA to settle all of AIFA's claims relating to sales of TYSABRI in excess of the reimbursement limit for the periods between February 2009 through February 2013 for an aggregate repayment of EUR33.3 million. As part of this settlement, we also agreed that the reimbursement limit will no longer be in effect as of February 2013. The settlement is pending approval by the Italy Avvocatura Generale dello Stato and the board of directors of AIFA. Upon this approval and the execution of the settlement, we will dismiss our appeal. Average Manufacturer Price Litigation On September 6, 2011, we and several other pharmaceutical companies were served with a complaint originally filed under seal on October 28, 2008 in the United States District Court for the Eastern District of Pennsylvania by Ronald Streck (the relator) on behalf of himself and the United States, and the states of New Jersey, California, Rhode Island, Michigan, Montana, Wisconsin, Massachusetts, Tennessee, Oklahoma, Texas, Indiana, New Hampshire, North Carolina, Florida, Georgia, New Mexico, Illinois, New York, Virginia, Delaware, Hawaii, Louisiana, Connecticut, and Nevada (collectively, the States), and the District of Columbia, alleging violations of the False Claims Act, 31 U.S.C. § 3729 et seq. and state and District of Columbia statutory counterparts. The United States and the States have declined to intervene, and the District of Columbia has not intervened. The complaint as amended alleges that Biogen Idec and other defendants underreport Average Manufacturer Price (AMP) information to the Centers for Medicare and Medicaid Services, thereby causing Biogen Idec and the other defendants to underpay rebates under the Medicaid Drug Rebate Program. The relator alleges that the underreporting has occurred because Biogen Idec and other defendants improperly consider various payments that they make to drug wholesalers to be discounts under applicable federal law. On July 3, 2012, the court dismissed all state and federal claims as to AMP submissions before January 1, 2007, and dismissed the remaining state-law claims in whole as to claims under New Mexico law and in part as to claims under the laws of Delaware, New Hampshire, Texas, Connecticut, Georgia, Indiana, Montana, New York, Oklahoma, and Rhode Island. The court denied our motion to dismiss federal law claims as to AMP submissions after January 1, 2007. A trial has been set for September 2014. We have not formed an opinion that an unfavorable outcome under the remaining claims is either “probable” or “remote,” and are unable at this stage of the litigation to form an opinion as to the magnitude or range of any potential loss. We believe that we have good and valid defenses and intend to vigorously defend against the allegations. Government Review of Sales and Promotional Practices We have learned that state and federal governmental authorities are investigating our sales and promotional practices. We are cooperating with the government. Qui Tam Litigation In August, 2012, we learned that a relator, on behalf of the United States and certain states, filed a suit under seal on February 17, 2011 against us, Elan Corporation, plc, and Elan Pharmaceuticals, Inc. in the United States District Court for the Western District of Virginia. We have neither seen nor been served with the complaint, but understand that it was filed under the Federal False Claims Act. Canada Lease Dispute On April 18, 2008, First Real Properties Limited filed suit against Biogen Idec Canada Inc. (BI Canada) in the Superior Court of Justice in London, Ontario alleging breach of an offer for lease of property signed by BI Canada in 2007 and an unsigned proposed lease for the same property. The plaintiff's complaint seeks $7.0 million in damages, but the plaintiff submitted an expert report estimating the plaintiff's damages to be approximately $2.5 million after mitigation. The plaintiff also seeks costs of approximately $0.4 million and interest. A trial occurred in February 2013 and the decision is pending. Knopp Neurosciences Dispute On February 25, 2013, Knopp filed suit against Biogen Idec International Holding Ltd. in the United States District Court for the District of Massachusetts, alleging that Biogen Idec wrongfully terminated its license agreement with Knopp for the development of a product for ALS. Knopp seeks damages and injunctive relief. Knopp had also sought the transfer of certain biosamples, but the court dismissed that claim with prejudice in June 2013. No trial date has been set for Knopp's remaining claims. We have not formed an opinion that an unfavorable outcome is either “probable” or “remote,” and are unable at this stage of the litigation to form an opinion as to the magnitude or range of any potential loss. We believe that we have good and valid defenses and are vigorously defending against the claims. Product Liability and Other Legal Proceedings We are also involved in product liability claims and other legal proceedings generally incidental to our normal business activities. While the outcome of any of these proceedings cannot be accurately predicted, we do not believe the ultimate resolution of any of these existing matters would have a material adverse effect on our business or financial condition.

Litigation

Massachusetts Department of Revenue

On June 8, 2010, we received Notices of Assessment from the Massachusetts DOR against BIMA for the payment of additional corporate excise tax, including associated interest and penalties, related to our 2004, 2005 and 2006 state tax filings. On February 3, 2011, we filed a petition with the Massachusetts ATB appealing the denial of our application for abatement, and on October 15, 2013 we reached a settlement resolving the dispute.

Hoechst — Genentech Arbitration

On October 24, 2008, Hoechst GmbH (Hoechst), an affiliate of Sanofi-Aventis Deutschland GmbH (Sanofi), filed a request for arbitration with the ICC International Court of Arbitration (Paris) claiming that Genentech breached a license agreement, now terminated, under which Hoechst claims rights (the Hoechst License). The Hoechst License granted Genentech certain rights with respect to U.S. Patents 5,849,522 (’522 patent) and 6,218,140 (’140 patent). In 2012, the arbitrator ruled that Genentech is liable to Hoechst for license royalties with respect to sales of RITUXAN, and in February 2013 he awarded Hoechst royalties of EUR108 million together with interest (estimated by Hoechst to be approximately EUR54 million as of the date of the award). Genentech has filed Declarations of Appeal in the Paris Court of Appeal to vacate the arbitral awards in their entirety and those annulment proceedings are pending. Genentech nonetheless paid Hoechst the amounts that Hoechst claims that it is owed, while reserving all legal rights, including the right to challenge the awards and the right to claim reimbursement.

Although we are not a party to the arbitration, we expect that amounts paid by Genentech and not ultimately recovered from Hoechst may be a cost charged to our collaboration with Genentech. Our revenues from unconsolidated joint business were reduced by approximately $50.0 million in the second quarter of 2011 and by approximately $41.5 million in the first quarter of 2013 to reflect our share of the royalties awarded to Hoechst and the interest Hoechst claims. Our share may vary from these amounts if Genentech is successful in challenging the awards.

Sanofi ’522 and ’140 Patent Litigation

On October 27, 2008, Sanofi filed suit against Genentech and Biogen Idec in the United States District Court for the Eastern District of Texas claiming that RITUXAN infringes the ’522 patent and the ’140 patent. That action was transferred and consolidated with an action filed on the same day by Genentech and Biogen Idec against Sanofi in the United States District for the Northern District of California seeking declaratory judgments that RITUXAN does not infringe the patents and that the asserted patent claims are invalid and unenforceable. On April 21, 2011, the federal court in California entered a separate and final judgment of non-infringement, and the United States Court of Appeals for the Federal Circuit affirmed on March 22, 2012. The federal court in California has stayed further proceedings relating to Biogen Idec's and Genentech's claims for a declaration that the asserted patent claims are invalid and unenforceable, and no trial date has been set on those claims.

’755 Patent Litigation

On September 15, 2009, we were issued U.S. Patent No. 7,588,755 (’755 Patent), which claims the use of interferon beta for immunomodulation or treating a viral condition, viral disease, cancers or tumors. This patent, which expires in September 2026, covers, among other things, the treatment of MS with our product AVONEX. On May 27, 2010, Bayer Healthcare Pharmaceuticals Inc. (Bayer) filed a lawsuit against us in the U.S. District Court for the District of New Jersey seeking a declaratory judgment of patent invalidity and non-infringement and seeking monetary relief in the form of attorneys' fees, costs and expenses. On May 28, 2010, BIMA filed a lawsuit in the U.S. District Court for the District of New Jersey alleging infringement of the ’755 Patent by EMD Serono, Inc. (manufacturer, marketer and seller of REBIF), Pfizer, Inc. (co-marketer of REBIF), Bayer (manufacturer, marketer and seller of BETASERON and manufacturer of EXTAVIA), and Novartis Pharmaceuticals Corp. (marketer and seller of EXTAVIA) and seeking monetary damages, including lost profits and royalties. The court has consolidated the two lawsuits, and we refer to the two actions as the “Consolidated ’755 Patent Actions”.

Bayer, Pfizer, Novartis and EMD Serono have all filed counterclaims in the Consolidated ’755 Patent Actions seeking declaratory judgments of patent invalidity and non-infringement, and seeking monetary relief in the form of costs and attorneys' fees, and EMD Serono and Bayer have each filed a counterclaim seeking a declaratory judgment that the ’755 Patent is unenforceable based on alleged inequitable conduct. Bayer has also amended its complaint to seek such a declaration. No trial date has been set.

Novartis V&D ’688 Patent Litigation

On January 26, 2011, Novartis Vaccines and Diagnostics, Inc. (Novartis V&D) filed suit against us in the United States District Court for the District of Delaware, alleging that TYSABRI infringes U.S. Patent No. 5,688,688 “Vector for Expression of a Polypeptide in a Mammalian Cell” (’688 Patent), which was granted in November 1997 and expires in November 2014. Novartis V&D seeks a declaration of infringement, a finding of willful infringement, compensatory damages in the form of a royalty and lost profits, treble damages, interest, costs and attorneys' fees. On July 18, 2012, the court granted Novartis V&D leave to add Novartis Pharma AG, an alleged exclusive licensee of the ’688 Patent, as co-plaintiff. We have not formed an opinion that an unfavorable outcome is either “probable” or “remote”, and are unable to estimate the magnitude or range of any potential loss. We believe that we have good and valid defenses to the complaint and will vigorously defend against it. A trial on liability has been set for January 2014.

Italian National Medicines Agency

In the fourth quarter of 2011, Biogen Idec SRL received a notice from the Italian National Medicines Agency (Agenzia Italiana del Farmaco or AIFA) stating that sales of TYSABRI for the period from February 2009 through February 2011 exceeded by EUR30.7 million a reimbursement limit established pursuant to a Price Determination Resolution (Price Resolution) granted by AIFA in December 2006. The Price Resolution set the initial price for the sale of TYSABRI in Italy and limited the amount of government reimbursement “for the first 24 months” of TYSABRI sales. As the basis for the claim, the AIFA notice referred to a 2001 Decree that provides for an automatic 24-month renewal of the terms of all Price Resolutions that are not renegotiated prior to the expiration of their term.

On November 17, 2011, Biogen Idec SRL responded to AIFA that the reimbursement limit in the Price Resolution by its terms applied only to the first 24 months of TYSABRI sales, which began in February 2007. On December 23, 2011, we filed an appeal in the Regional Administrative Tribunal of Lazio (Il Tribunale Amministrativo Regionale per il Lazio) in Rome against AIFA, seeking a ruling that our interpretation of the Price Resolution is valid and that the position of AIFA is unenforceable, and the appeal is pending. On November 21, 2012, the tribunal ruled that the reimbursement limit would not automatically renew for another 24-month term pending resolution of the dispute.

In June 2013, the Price and Reimbursement Committee of AIFA informed Biogen Idec SRL that sales of TYSABRI for February 2011 through February 2013 exceeded the reimbursement limit in the Price Resolution. We dispute that the reimbursement limit applies to this period for the same reason that we dispute its application to the February 2009 through February 2011 period.

In July 2013, we reached an agreement in principle with the Price and Reimbursement Committee of AIFA to settle all of AIFA's claims relating to sales of TYSABRI in excess of the reimbursement limit for the periods between February 2009 through February 2013 for an aggregate repayment of EUR33.3 million. As part of this settlement, we also agreed that the reimbursement limit will no longer be in effect as of February 2013. The settlement is pending approval by the Italy Avvocatura Generale dello Stato and the board of directors of AIFA. Upon this approval and the execution of the settlement, we will dismiss our appeal.

Average Manufacturer Price Litigation

On September 6, 2011, we and several other pharmaceutical companies were served with a complaint originally filed under seal on October 28, 2008 in the United States District Court for the Eastern District of Pennsylvania by Ronald Streck (the relator) on behalf of himself and the United States, and the states of New Jersey, California, Rhode Island, Michigan, Montana, Wisconsin, Massachusetts, Tennessee, Oklahoma, Texas, Indiana, New Hampshire, North Carolina, Florida, Georgia, New Mexico, Illinois, New York, Virginia, Delaware, Hawaii, Louisiana, Connecticut, and Nevada (collectively, the States), and the District of Columbia, alleging violations of the False Claims Act, 31 U.S.C. § 3729 et seq. and state and District of Columbia statutory counterparts. The United States and the States have declined to intervene, and the District of Columbia has not intervened. The complaint as amended alleges that Biogen Idec and other defendants underreport Average Manufacturer Price (AMP) information to the Centers for Medicare and Medicaid Services, thereby causing Biogen Idec and the other defendants to underpay rebates under the Medicaid Drug Rebate Program. The relator alleges that the underreporting has occurred because Biogen Idec and other defendants improperly consider various payments that they make to drug wholesalers to be discounts under applicable federal law. On July 3, 2012, the court dismissed all state and federal claims as to AMP submissions before January 1, 2007, and dismissed the remaining state-law claims in whole as to claims under New Mexico law and in part as to claims under the laws of Delaware, New Hampshire, Texas, Connecticut, Georgia, Indiana, Montana, New York, Oklahoma, and Rhode Island. The court denied our motion to dismiss federal law claims as to AMP submissions after January 1, 2007. A trial has been set for September 2014. We have not formed an opinion that an unfavorable outcome under the remaining claims is either “probable” or “remote,” and are unable at this stage of the litigation to form an opinion as to the magnitude or range of any potential loss. We believe that we have good and valid defenses and intend to vigorously defend against the allegations.

Government Review of Sales and Promotional Practices

We have learned that state and federal governmental authorities are investigating our sales and promotional practices. We are cooperating with the government.

Qui Tam Litigation

In August, 2012, we learned that a relator, on behalf of the United States and certain states, filed a suit under seal on February 17, 2011 against us, Elan Corporation, plc, and Elan Pharmaceuticals, Inc. in the United States District Court for the Western District of Virginia. We have neither seen nor been served with the complaint, but understand that it was filed under the Federal False Claims Act.

Canada Lease Dispute

On April 18, 2008, First Real Properties Limited filed suit against Biogen Idec Canada Inc. (BI Canada) in the Superior Court of Justice in London, Ontario alleging breach of an offer for lease of property signed by BI Canada in 2007 and an unsigned proposed lease for the same property. The plaintiff's complaint seeks $7.0 million in damages, but the plaintiff submitted an expert report estimating the plaintiff's damages to be approximately $2.5 million after mitigation. The plaintiff also seeks costs of approximately $0.4 million and interest. A trial occurred in February 2013 and the decision is pending.

Knopp Neurosciences Dispute

On February 25, 2013, Knopp filed suit against Biogen Idec International Holding Ltd. in the United States District Court for the District of Massachusetts, alleging that Biogen Idec wrongfully terminated its license agreement with Knopp for the development of a product for ALS. Knopp seeks damages and injunctive relief. Knopp had also sought the transfer of certain biosamples, but the court dismissed that claim with prejudice in June 2013. No trial date has been set for Knopp's remaining claims. We have not formed an opinion that an unfavorable outcome is either “probable” or “remote,” and are unable at this stage of the litigation to form an opinion as to the magnitude or range of any potential loss. We believe that we have good and valid defenses and are vigorously defending against the claims.

Product Liability and Other Legal Proceedings

We are also involved in product liability claims and other legal proceedings generally incidental to our normal business activities. While the outcome of any of these proceedings cannot be accurately predicted, we do not believe the ultimate resolution of any of these existing matters would have a material adverse effect on our business or financial condition.