2.2.0.7 false Revenue Recognition (Policies) 0403 - Disclosure - Revenue Recognition (Policies) true false false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ 2 0 biib_RevenueRecognitionPoliciesAbstract biib false na duration Revenue recognition. false false false false false true false false false false false false 1 false false false false 0 0 false false false xbrli:stringItemType string Revenue recognition. false 3 1 us-gaap_RevenueRecognitionPolicyTextBlock us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 <!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --> <!-- Begin Block Tagged Accounting Policy: biib-20100930_note3_accounting_policy_table1 - us-gaap:RevenueRecognitionPolicyTextBlock--> <div align="left" style="font-size: 10pt; font-family: 'Times New Roman', Times"> <div style="margin-top: 6pt; font-size: 1pt">&#160; </div> <div align="left" style="margin-left: 0%; margin-right: 0%; text-indent: 4%; font-size: 10pt; font-family: 'Times New Roman', Times; color: #000000; background: transparent"> During the third quarter of 2010, we elected to early adopt Accounting Standards Update (ASU) <font style="white-space: nowrap">No.&#160;2009-13,</font> <i>Multiple-Deliverable Revenue Arrangements </i>(ASU <font style="white-space: nowrap">2009-13).</font> <font style="white-space: nowrap">ASU&#160;2009-13,</font> amends existing revenue recognition accounting pronouncements and provides accounting principles and application guidance on whether multiple deliverables exist, how the arrangement should be separated, and the consideration allocated. This guidance eliminates the requirement to establish the fair value of undelivered products and services and instead provides for separate revenue recognition based upon management&#8217;s estimate of the selling price for an undelivered item when there is no other means to determine the fair value of that undelivered item. Previous accounting principles required that the fair value of the undelivered item be the price of the item either sold in a separate transaction between unrelated third parties or the price charged for each item when the item is sold separately by the vendor. The early adoption of this standard requires the disclosure of the effect of this guidance as applied to all previously reported interim periods in the fiscal year of adoption. Our adoption of this standard did not have a material impact our financial position or results of operations as through the third quarter of 2010, we had not recorded any revenue in accordance with revenue recognition rules for multiple deliverables as described in ASU <font style="white-space: nowrap">2009-13</font> or its predecessor pronouncements. </div> </div> <!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --> <!-- Begin Block Tagged false false false us-types:textBlockItemType textblock Describes an entity's accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction should be disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section B -Paragraph Question 1 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 22 -Paragraph 8, 12, 13 false 1 2 false UnKnown UnKnown UnKnown false true