2.2.0.7falseNew Accounting Pronouncements (Policies)0420 - Disclosure - New Accounting Pronouncements (Policies)truefalsefalsefalse1USDfalsefalseUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0$20biib_NewAccountingPronouncementsPoliciesAbstractbiibfalsenadurationNew Accounting Pronouncements.falsefalsefalsefalsefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalsefalse00falsefalsefalsexbrli:stringItemTypestringNew Accounting Pronouncements.false31biib_AdoptionOfAsuNo201017AndItsEffectTextBlockbiibfalsenadurationAdoption of ASU No. 2010-17 and its effect.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabelfalse1falsefalsefalsefalse00<!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" -->
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In April 2010, the FASB issued ASU
<font style="white-space: nowrap">No. 2010-17,</font>
<i>Revenue Recognition — Milestone Method </i>(ASU
<font style="white-space: nowrap">2010-017).</font>
ASU <font style="white-space: nowrap">2010-017</font>
provides guidance in applying the milestone method of revenue
recognition to research or development arrangements. Under this
guidance management may recognize revenue contingent upon the
achievement of a milestone in its entirety, in the period in
which the milestone is achieved, only if the milestone meets all
the criteria within the guidance to be considered substantive.
This ASU is effective on a prospective basis for research and
development milestones achieved in fiscal years, beginning on or
after June 15, 2010, which for Biogen Idec means fiscal
2011. Early adoption is permitted; however, adoption of this
guidance as of a date other than January 1, 2011 will
require us to apply this guidance retrospectively effective as
of January 1, 2010 and will require disclosure of the
effect of this guidance as applied to all previously reported
interim periods in the fiscal year of adoption. As we plan to
implement
<font style="white-space: nowrap">ASU 2010-17</font>
prospectively, the effect of this guidance will be limited to
future transactions. We do not expect adoption of this standard
to have a material impact on our financial position or results
of operations as we have no material research and development
arrangements which will be accounted for under the milestone
method.
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