<SEC-DOCUMENT>0001193125-23-245816.txt : 20230928
<SEC-HEADER>0001193125-23-245816.hdr.sgml : 20230928
<ACCEPTANCE-DATETIME>20230928172554
ACCESSION NUMBER:		0001193125-23-245816
CONFORMED SUBMISSION TYPE:	8-K/A
PUBLIC DOCUMENT COUNT:		12
CONFORMED PERIOD OF REPORT:	20230626
ITEM INFORMATION:		Submission of Matters to a Vote of Security Holders
FILED AS OF DATE:		20230928
DATE AS OF CHANGE:		20230928

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOGEN INC.
		CENTRAL INDEX KEY:			0000875045
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				330112644
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		8-K/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19311
		FILM NUMBER:		231291010

	BUSINESS ADDRESS:	
		STREET 1:		225 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		7814642000

	MAIL ADDRESS:	
		STREET 1:		225 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOGEN IDEC INC.
		DATE OF NAME CHANGE:	20070427

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOGEN IDEC INC
		DATE OF NAME CHANGE:	20031112

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	IDEC PHARMACEUTICALS CORP / DE
		DATE OF NAME CHANGE:	19970530
</SEC-HEADER>
<DOCUMENT>
<TYPE>8-K/A
<SEQUENCE>1
<FILENAME>d534386d8ka.htm
<DESCRIPTION>8-K/A
<TEXT>
<XBRL>
<?xml version="1.0" encoding="utf-8" ?>
<html xmlns:dei="http://xbrl.sec.gov/dei/2022" xmlns:us-types="http://fasb.org/us-types/2022" xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:biib="http://www.biogenidec.com/20230626" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:utr="http://www.xbrl.org/2009/utr" xmlns:iso4217="http://www.xbrl.org/2003/iso4217" xmlns:ix="http://www.xbrl.org/2013/inlineXBRL" xmlns:ixt="http://www.xbrl.org/inlineXBRL/transformation/2015-02-26" xmlns:ixt-sec="http://www.sec.gov/inlineXBRL/transformation/2015-08-31" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>8-K/A</title>
<meta http-equiv="Content-Type" content="text/html" />
</head>
   <body><div style="display:none"> <ix:header> <ix:hidden> <ix:nonNumeric name="dei:AmendmentFlag" contextRef="duration_2023-06-26_to_2023-06-26">true</ix:nonNumeric> <ix:nonNumeric id="Hidden_dei_EntityCentralIndexKey" name="dei:EntityCentralIndexKey" contextRef="duration_2023-06-26_to_2023-06-26">0000875045</ix:nonNumeric> </ix:hidden> <ix:references> <link:schemaRef xlink:type="simple" xlink:href="biib-20230626.xsd" xlink:arcrole="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase"></link:schemaRef> </ix:references> <ix:resources> <xbrli:context id="duration_2023-06-26_to_2023-06-26"> <xbrli:entity> <xbrli:identifier scheme="http://www.sec.gov/CIK">0000875045</xbrli:identifier> </xbrli:entity> <xbrli:period> <xbrli:startDate>2023-06-26</xbrli:startDate> <xbrli:endDate>2023-06-26</xbrli:endDate> </xbrli:period> </xbrli:context> </ix:resources> </ix:header> </div> <div style="text-align:center"> <div style="width:8.5in;text-align:left;margin-left: auto;margin-right: auto"> <p style="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&#160;</p> <p style="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&#160;</p> <p style="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman;font-weight:bold;text-align:center">UNITED STATES</p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman;font-weight:bold;text-align:center">SECURITIES AND EXCHANGE COMMISSION</p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman;font-weight:bold;text-align:center">Washington, D.C. 20549</p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p> <div style="text-align:center"> <p style="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%;text-align:center;margin-left: auto;margin-right: auto">&#160;</p></div> <p style="margin-top:10pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman;font-weight:bold;text-align:center">FORM <ix:nonNumeric name="dei:DocumentType" contextRef="duration_2023-06-26_to_2023-06-26">8-K/A</ix:nonNumeric></p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p> <div style="text-align:center"> <p style="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%;text-align:center;margin-left: auto;margin-right: auto">&#160;</p></div> <p style="margin-top:10pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman;font-weight:bold;text-align:center">CURRENT REPORT</p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman;font-weight:bold;text-align:center">Pursuant to Section 13 or 15(d)</p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman;font-weight:bold;text-align:center">of the Securities Exchange Act of 1934</p> <p style="margin-top:10pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman;font-weight:bold;text-align:center">Date of Report (Date of earliest event reported): <ix:nonNumeric name="dei:DocumentPeriodEndDate" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt:datemonthdayyearen">June 26, 2023</ix:nonNumeric></p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p> <div style="text-align:center"> <p style="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%;text-align:center;margin-left: auto;margin-right: auto">&#160;</p></div> <p style="margin-top:10pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman;font-weight:bold;text-align:center"> <ix:nonNumeric name="dei:EntityRegistrantName" contextRef="duration_2023-06-26_to_2023-06-26">Biogen Inc.</ix:nonNumeric> </p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;font-weight:bold;text-align:center">(Exact name of Registrant as specified in its charter)</p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p> <div style="text-align:center"> <p style="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%;text-align:center;margin-left: auto;margin-right: auto">&#160;</p></div> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; font-family:Times New Roman; font-size:8pt;width:100%;border:0;margin:0 auto">
<tr>
<td style="width:34%"></td>
<td style="vertical-align:bottom"></td>
<td style="width:32%"></td>
<td style="vertical-align:bottom;width:1%"></td>
<td style="width:32%"></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style=" text-align: center;margin:auto; vertical-align:top"><span style="font-weight:bold"><ix:nonNumeric name="dei:EntityIncorporationStateCountryCode" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:stateprovnameen">Delaware</ix:nonNumeric></span></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; vertical-align:top"><span style="font-weight:bold"><ix:nonNumeric name="dei:EntityFileNumber" contextRef="duration_2023-06-26_to_2023-06-26">0-19311</ix:nonNumeric></span></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; vertical-align:top"><span style="font-weight:bold"><ix:nonNumeric name="dei:EntityTaxIdentificationNumber" contextRef="duration_2023-06-26_to_2023-06-26">33-0112644</ix:nonNumeric></span></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<td style=" text-align: center;margin:auto; vertical-align:top"> <p style="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">(State of</p> <p style="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">Incorporation)</p></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; vertical-align:top"> <p style="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">(Commission</p> <p style="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">File Number)</p></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; vertical-align:top"> <p style="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">(I.R.S. Employer</p> <p style="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">Identification No.)</p></td></tr></table> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; font-family:Times New Roman; font-size:10pt;width:100%;border:0;margin:0 auto">
<tr>
<td style="width:99%"></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style=" text-align: center;margin:auto; vertical-align:top"><span style="font-weight:bold"><ix:nonNumeric name="dei:EntityAddressAddressLine1" contextRef="duration_2023-06-26_to_2023-06-26">225 Binney Street</ix:nonNumeric>, <ix:nonNumeric name="dei:EntityAddressCityOrTown" contextRef="duration_2023-06-26_to_2023-06-26">Cambridge</ix:nonNumeric>, <ix:nonNumeric name="dei:EntityAddressStateOrProvince" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:stateprovnameen">Massachusetts</ix:nonNumeric> <ix:nonNumeric name="dei:EntityAddressPostalZipCode" contextRef="duration_2023-06-26_to_2023-06-26">02142</ix:nonNumeric></span></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<td style=" text-align: center;margin:auto; vertical-align:top"><span style="font-weight:bold">(Address of principal executive offices, including zip code)</span></td></tr></table> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;font-weight:bold;text-align:center"><ix:nonNumeric name="dei:CityAreaCode" contextRef="duration_2023-06-26_to_2023-06-26">(617)</ix:nonNumeric> <ix:nonNumeric name="dei:LocalPhoneNumber" contextRef="duration_2023-06-26_to_2023-06-26">679-2000</ix:nonNumeric></p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">(Registrant&#8217;s telephone number, including area code)</p> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;font-weight:bold;text-align:center">Not Applicable</p> <p style="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">(Former Name or Former Address, if Changed Since Last Report)</p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p> <div style="text-align:center"> <p style="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%;text-align:center;margin-left: auto;margin-right: auto">&#160;</p></div> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the Registrant under any of the following provisions:</p> <p style="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table style="border-collapse:collapse; font-family:Times New Roman; font-size:10pt;border:0;width:100%" cellpadding="0" cellspacing="0">
<tr style="page-break-inside:avoid">
<td style="width:4%;vertical-align:top"><ix:nonNumeric name="dei:WrittenCommunications" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:boolballotbox">&#9744;</ix:nonNumeric></td>
<td style="vertical-align:top"> <p style=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;text-align:left">Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)</p></td></tr></table> <p style="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table style="border-collapse:collapse; font-family:Times New Roman; font-size:10pt;border:0;width:100%" cellpadding="0" cellspacing="0">
<tr style="page-break-inside:avoid">
<td style="width:4%;vertical-align:top"><ix:nonNumeric name="dei:SolicitingMaterial" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:boolballotbox">&#9744;</ix:nonNumeric></td>
<td style="vertical-align:top"> <p style=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;text-align:left">Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)</p></td></tr></table> <p style="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table style="border-collapse:collapse; font-family:Times New Roman; font-size:10pt;border:0;width:100%" cellpadding="0" cellspacing="0">
<tr style="page-break-inside:avoid">
<td style="width:4%;vertical-align:top"><ix:nonNumeric name="dei:PreCommencementTenderOffer" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:boolballotbox">&#9744;</ix:nonNumeric></td>
<td style="vertical-align:top"> <p style=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;text-align:left">Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))</p></td></tr></table> <p style="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table style="border-collapse:collapse; font-family:Times New Roman; font-size:10pt;border:0;width:100%" cellpadding="0" cellspacing="0">
<tr style="page-break-inside:avoid">
<td style="width:4%;vertical-align:top"><ix:nonNumeric name="dei:PreCommencementIssuerTenderOffer" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:boolballotbox">&#9744;</ix:nonNumeric></td>
<td style="vertical-align:top"> <p style=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;text-align:left">Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))</p></td></tr></table> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Securities registered pursuant to Section 12(b) of the Act:</p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; font-family:Times New Roman; font-size:8pt;width:100%;border:0;margin:0 auto">
<tr>
<td style="width:34%"></td>
<td style="vertical-align:bottom"></td>
<td style="width:32%"></td>
<td style="vertical-align:bottom;width:1%"></td>
<td style="width:32%"></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<td style=" text-align: center;margin:auto; border-bottom:1.00pt solid #000000;vertical-align:bottom;white-space:nowrap"> <p style="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">Title of each class</p></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; border-bottom:1.00pt solid #000000;vertical-align:bottom"> <p style="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">Trading<br />Symbol(s)</p></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; border-bottom:1.00pt solid #000000;vertical-align:bottom"> <p style="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">Name of each exchange</p> <p style="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman;font-weight:bold;text-align:center">on which registered</p></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style=" text-align: center;margin:auto; vertical-align:top"><ix:nonNumeric name="dei:Security12bTitle" contextRef="duration_2023-06-26_to_2023-06-26">Common Stock, $0.0005 par value</ix:nonNumeric></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; vertical-align:top"><ix:nonNumeric name="dei:TradingSymbol" contextRef="duration_2023-06-26_to_2023-06-26">BIIB</ix:nonNumeric></td>
<td style="vertical-align:bottom">&#160;</td>
<td style=" text-align: center;margin:auto; vertical-align:top"><ix:nonNumeric name="dei:SecurityExchangeName" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:exchnameen">The Nasdaq Global Select Market</ix:nonNumeric></td></tr></table> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark whether the Registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR &#167;230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR &#167;240.12b-2).</p> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Emerging growth company <ix:nonNumeric name="dei:EntityEmergingGrowthCompany" contextRef="duration_2023-06-26_to_2023-06-26" format="ixt-sec:boolballotbox">&#9744;</ix:nonNumeric></p> <p style="margin-top:10pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">If an emerging growth company, indicate by check mark if the Registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section&#160;13(a) of the Exchange Act. &#9744;</p> <p style="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&#160;</p> <p style="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&#160;</p> <p style="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&#160;</p></div></div>

<p style="margin-top:1em; margin-bottom:0em; page-break-before:always"> </p>
<hr style="color:#999999;height:3px;width:100%" />

<div style="text-align:center"><div style="width:8.5in;text-align:left;margin-left: auto;margin-right: auto">
 <p style="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;font-weight:bold">Explanatory Note </p> <p style="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><ix:nonNumeric name="dei:AmendmentDescription" contextRef="duration_2023-06-26_to_2023-06-26">This Current Report on Form <span style="white-space:nowrap">8-K/A</span> (this &#8220;Amendment&#8221;) amends the Current Report on Form <span style="white-space:nowrap">8-K</span> of Biogen Inc. (the &#8220;Company&#8221;) filed with the U.S. Securities and Exchange Commission on June&#160;29, 2023 (the &#8220;Original Form <span style="white-space:nowrap">8-K&#8221;).</span> The Original Form <span style="white-space:nowrap">8-K</span> reported the final voting results of the Company&#8217;s 2023 Annual Meeting of Stockholders held on June&#160;26, 2023 (the &#8220;Annual Meeting&#8221;). The sole purpose of this Amendment is to disclose the Company&#8217;s decision regarding whether stockholder votes to approve the compensation of its named executive officers required by Section&#160;14A(a)(1) of the Securities Exchange Act of 1934 and Rule <span style="white-space:nowrap">14a-21(a)</span> promulgated thereunder (the <span style="white-space:nowrap"><span style="white-space:nowrap">&#8220;Say-on-Pay</span></span> Vote&#8221;) should be held every one, two or three years (the <span style="white-space:nowrap"><span style="white-space:nowrap">&#8220;Say-on-Frequency</span></span> Proposal&#8221;). No other changes have been made to the Original Form <span style="white-space:nowrap">8-K.</span></ix:nonNumeric> </p> <p style="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&#160;</p>
<table style="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt;border:0;width:100%" cellpadding="0" cellspacing="0">
<tr style="page-break-inside:avoid">
<td style="width:11%;vertical-align:top" align="left"><span style="font-weight:bold">Item&#8201;5.07</span></td>
<td align="left" style="vertical-align:top"> <p style=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;font-weight:bold;text-align:left">Submission of Matters to a Vote of Security Holders. </p></td></tr></table> <p style="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">As previously reported on the Original Form <span style="white-space:nowrap">8-K,</span> in an advisory vote held at the Annual Meeting on the <span style="white-space:nowrap"><span style="white-space:nowrap">Say-on-Frequency</span></span> Proposal, the Company&#8217;s stockholders expressed their preference for a <span style="white-space:nowrap"><span style="white-space:nowrap">Say-on-Pay</span></span> Vote to be conducted every year. The Company&#8217;s Board of Directors considered the outcome of this advisory vote and determined that future <span style="white-space:nowrap"><span style="white-space:nowrap">Say-on-Pay</span></span> Votes will be conducted every year. The Company&#8217;s Board of Directors will <span style="white-space:nowrap">re-evaluate</span> this determination after the next <span style="white-space:nowrap"><span style="white-space:nowrap">Say-on-Frequency</span></span> Proposal, which will be held no later than the 2029 annual meeting of stockholders. </p>
</div></div>



<p style="margin-top:1em; margin-bottom:0em; page-break-before:always"> </p>
<hr style="color:#999999;height:3px;width:100%" />

<div style="text-align:center"><div style="width:8.5in;text-align:left;margin-left: auto;margin-right: auto">
 <p style="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman;font-weight:bold;text-align:center">SIGNATURES </p> <p style="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. </p> <p style="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&#160;</p><div>
<table cellspacing="0" cellpadding="0" style="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt;width:40%;border:0;margin-left:auto">


<tr>

<td style="width:7%"></td>

<td style="vertical-align:bottom;width:1%"></td>
<td style="width:92%"></td></tr>


<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style="vertical-align:bottom" colspan="3"><span style="font-weight:bold">BIOGEN INC.</span></td></tr>
<tr style="font-size:1pt">
<td style="height:12pt"></td>
<td style="height:12pt" colspan="2"></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style="vertical-align:top">By:</td>
<td style="vertical-align:bottom">&#160;</td>
<td style="vertical-align:bottom"> <p style="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Wendell Taylor</p></td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style="vertical-align:bottom"></td>
<td style="vertical-align:bottom">&#160;</td>
<td style="vertical-align:top">Name: Wendell Taylor</td></tr>
<tr style="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<td style="vertical-align:bottom"></td>
<td style="vertical-align:bottom">&#160;</td>
<td style="vertical-align:top">Title: &#8194;&#8201;Chief Corporation Counsel</td></tr>
</table></div> <p style="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Dated: September&#160;28, 2023 </p>
</div></div>

</body></html>
</XBRL>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-101.SCH
<SEQUENCE>2
<FILENAME>biib-20230626.xsd
<DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA
<TEXT>
<XBRL>
<?xml version="1.0" encoding="us-ascii"?>
<!-- DFIN - https://www.dfinsolutions.com/ -->
<!-- CTU Version: Release master Build:20221108.6 -->
<!-- Creation date: 9/28/2023 11:09:13 PM Eastern Time -->
<!-- Copyright (c) 2023 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema
  xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric"
  xmlns:num="http://www.xbrl.org/dtr/type/numeric"
  xmlns:us-types="http://fasb.org/us-types/2022"
  xmlns:biib="http://www.biogenidec.com/20230626"
  xmlns:dei="http://xbrl.sec.gov/dei/2022"
  xmlns:xbrli="http://www.xbrl.org/2003/instance"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xbrldt="http://xbrl.org/2005/xbrldt"
  attributeFormDefault="unqualified"
  elementFormDefault="qualified"
  targetNamespace="http://www.biogenidec.com/20230626"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance" />
    <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase" />
    <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2022/dei-2022.xsd" namespace="http://xbrl.sec.gov/dei/2022" />
    <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/numeric" />
    <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/non-numeric" />
    <xsd:import schemaLocation="https://xbrl.sec.gov/naics/2022/naics-2022.xsd" namespace="http://xbrl.sec.gov/naics/2022" />
    <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt" />
  <xsd:annotation>
    <xsd:appinfo>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="biib-20230626_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Label Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="biib-20230626_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation Links, all" xlink:type="simple" />
      <link:roleType roleURI="http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
</xsd:schema>
</XBRL>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-101.LAB
<SEQUENCE>3
<FILENAME>biib-20230626_lab.xml
<DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE
<TEXT>
<XBRL>
<?xml version="1.0" encoding="us-ascii" standalone="yes"?>
<!-- DFIN - https://www.dfinsolutions.com/ -->
<!-- CTU Version: Release master Build:20221108.6 -->
<!-- Creation date: 9/28/2023 11:09:13 PM Eastern Time -->
<!-- Copyright (c) 2023 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<link:linkbase
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:labelLink xlink:role="http://www.xbrl.org/2003/role/link" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CoverAbstract" xlink:type="locator" xlink:label="dei_CoverAbstract" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_CoverAbstract" xlink:to="dei_CoverAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_CoverAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cover [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_CoverAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cover [Abstract]</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_AmendmentFlag" xlink:type="locator" xlink:label="dei_AmendmentFlag" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AmendmentFlag" xlink:to="dei_AmendmentFlag_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_AmendmentFlag_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amendment Flag</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_AmendmentFlag_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amendment Flag</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCentralIndexKey" xlink:type="locator" xlink:label="dei_EntityCentralIndexKey" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityCentralIndexKey" xlink:to="dei_EntityCentralIndexKey_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityCentralIndexKey_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Central Index Key</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityCentralIndexKey_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Central Index Key</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentType" xlink:type="locator" xlink:label="dei_DocumentType" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_DocumentType" xlink:to="dei_DocumentType_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_DocumentType_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Document Type</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_DocumentType_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Type</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentPeriodEndDate" xlink:type="locator" xlink:label="dei_DocumentPeriodEndDate" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_DocumentPeriodEndDate" xlink:to="dei_DocumentPeriodEndDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Document Period End Date</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Period End Date</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityRegistrantName" xlink:type="locator" xlink:label="dei_EntityRegistrantName" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityRegistrantName" xlink:to="dei_EntityRegistrantName_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityRegistrantName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Registrant Name</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityRegistrantName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Registrant Name</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityIncorporationStateCountryCode" xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityIncorporationStateCountryCode" xlink:to="dei_EntityIncorporationStateCountryCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation State Country Code</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Incorporation State Country Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityFileNumber" xlink:type="locator" xlink:label="dei_EntityFileNumber" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityFileNumber" xlink:to="dei_EntityFileNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity File Number</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity File Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityTaxIdentificationNumber" xlink:type="locator" xlink:label="dei_EntityTaxIdentificationNumber" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityTaxIdentificationNumber" xlink:to="dei_EntityTaxIdentificationNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Tax Identification Number</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Tax Identification Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressAddressLine1" xlink:type="locator" xlink:label="dei_EntityAddressAddressLine1" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityAddressAddressLine1" xlink:to="dei_EntityAddressAddressLine1_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, Address Line One</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Address Line One</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressCityOrTown" xlink:type="locator" xlink:label="dei_EntityAddressCityOrTown" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityAddressCityOrTown" xlink:to="dei_EntityAddressCityOrTown_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, City or Town</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, City or Town</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressStateOrProvince" xlink:type="locator" xlink:label="dei_EntityAddressStateOrProvince" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityAddressStateOrProvince" xlink:to="dei_EntityAddressStateOrProvince_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, State or Province</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, State or Province</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressPostalZipCode" xlink:type="locator" xlink:label="dei_EntityAddressPostalZipCode" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityAddressPostalZipCode" xlink:to="dei_EntityAddressPostalZipCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address, Postal Zip Code</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Postal Zip Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CityAreaCode" xlink:type="locator" xlink:label="dei_CityAreaCode" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_CityAreaCode" xlink:to="dei_CityAreaCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">City Area Code</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">City Area Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LocalPhoneNumber" xlink:type="locator" xlink:label="dei_LocalPhoneNumber" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_LocalPhoneNumber" xlink:to="dei_LocalPhoneNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Local Phone Number</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Local Phone Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_WrittenCommunications" xlink:type="locator" xlink:label="dei_WrittenCommunications" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_WrittenCommunications" xlink:to="dei_WrittenCommunications_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_WrittenCommunications_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Written Communications</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_WrittenCommunications_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Written Communications</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_SolicitingMaterial" xlink:type="locator" xlink:label="dei_SolicitingMaterial" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_SolicitingMaterial" xlink:to="dei_SolicitingMaterial_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_SolicitingMaterial_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Soliciting Material</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_SolicitingMaterial_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Soliciting Material</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_PreCommencementTenderOffer" xlink:type="locator" xlink:label="dei_PreCommencementTenderOffer" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_PreCommencementTenderOffer" xlink:to="dei_PreCommencementTenderOffer_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_PreCommencementTenderOffer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Pre Commencement Tender Offer</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_PreCommencementTenderOffer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Pre Commencement Tender Offer</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_PreCommencementIssuerTenderOffer" xlink:type="locator" xlink:label="dei_PreCommencementIssuerTenderOffer" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_PreCommencementIssuerTenderOffer" xlink:to="dei_PreCommencementIssuerTenderOffer_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_PreCommencementIssuerTenderOffer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Pre Commencement Issuer Tender Offer</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_PreCommencementIssuerTenderOffer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Pre Commencement Issuer Tender Offer</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_Security12bTitle" xlink:type="locator" xlink:label="dei_Security12bTitle" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_Security12bTitle" xlink:to="dei_Security12bTitle_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_Security12bTitle_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Security 12b Title</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_Security12bTitle_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Security 12b Title</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_TradingSymbol" xlink:type="locator" xlink:label="dei_TradingSymbol" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_TradingSymbol" xlink:to="dei_TradingSymbol_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_TradingSymbol_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Trading Symbol</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_TradingSymbol_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Trading Symbol</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_SecurityExchangeName" xlink:type="locator" xlink:label="dei_SecurityExchangeName" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_SecurityExchangeName" xlink:to="dei_SecurityExchangeName_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_SecurityExchangeName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Security Exchange Name</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_SecurityExchangeName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Security Exchange Name</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityEmergingGrowthCompany" xlink:type="locator" xlink:label="dei_EntityEmergingGrowthCompany" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityEmergingGrowthCompany" xlink:to="dei_EntityEmergingGrowthCompany_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Emerging Growth Company</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Emerging Growth Company</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_AmendmentDescription" xlink:type="locator" xlink:label="dei_AmendmentDescription" />
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AmendmentDescription" xlink:to="dei_AmendmentDescription_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_AmendmentDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amendment Description</link:label>
    <link:label xml:lang="en-US" xlink:label="dei_AmendmentDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amendment Description</link:label>
  </link:labelLink>
</link:linkbase>
</XBRL>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-101.PRE
<SEQUENCE>4
<FILENAME>biib-20230626_pre.xml
<DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE
<TEXT>
<XBRL>
<?xml version="1.0" encoding="us-ascii" standalone="yes"?>
<!-- DFIN - https://www.dfinsolutions.com/ -->
<!-- CTU Version: Release master Build:20221108.6 -->
<!-- Creation date: 9/28/2023 11:09:13 PM Eastern Time -->
<!-- Copyright (c) 2023 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<link:linkbase
    xmlns:link="http://www.xbrl.org/2003/linkbase"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xbrldt="http://xbrl.org/2005/xbrldt"
    xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation" xlink:href="biib-20230626.xsd#Role_DocumentDocumentAndEntityInformation" xlink:type="simple" />
  <link:presentationLink xlink:type="extended" xlink:role="http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation">
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CoverAbstract" xlink:type="locator" xlink:label="dei_CoverAbstract" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_AmendmentFlag" xlink:type="locator" xlink:label="dei_AmendmentFlag" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_AmendmentFlag" order="22.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCentralIndexKey" xlink:type="locator" xlink:label="dei_EntityCentralIndexKey" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityCentralIndexKey" order="23.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentType" xlink:type="locator" xlink:label="dei_DocumentType" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentType" order="25.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentPeriodEndDate" xlink:type="locator" xlink:label="dei_DocumentPeriodEndDate" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentPeriodEndDate" order="26.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityRegistrantName" xlink:type="locator" xlink:label="dei_EntityRegistrantName" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityRegistrantName" order="27.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityIncorporationStateCountryCode" xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityIncorporationStateCountryCode" order="28.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityFileNumber" xlink:type="locator" xlink:label="dei_EntityFileNumber" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityFileNumber" order="29.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityTaxIdentificationNumber" xlink:type="locator" xlink:label="dei_EntityTaxIdentificationNumber" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityTaxIdentificationNumber" order="30.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressAddressLine1" xlink:type="locator" xlink:label="dei_EntityAddressAddressLine1" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressAddressLine1" order="31.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressCityOrTown" xlink:type="locator" xlink:label="dei_EntityAddressCityOrTown" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressCityOrTown" order="32.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressStateOrProvince" xlink:type="locator" xlink:label="dei_EntityAddressStateOrProvince" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressStateOrProvince" order="33.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressPostalZipCode" xlink:type="locator" xlink:label="dei_EntityAddressPostalZipCode" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressPostalZipCode" order="34.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CityAreaCode" xlink:type="locator" xlink:label="dei_CityAreaCode" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_CityAreaCode" order="35.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LocalPhoneNumber" xlink:type="locator" xlink:label="dei_LocalPhoneNumber" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_LocalPhoneNumber" order="36.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_WrittenCommunications" xlink:type="locator" xlink:label="dei_WrittenCommunications" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_WrittenCommunications" order="37.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_SolicitingMaterial" xlink:type="locator" xlink:label="dei_SolicitingMaterial" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_SolicitingMaterial" order="38.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_PreCommencementTenderOffer" xlink:type="locator" xlink:label="dei_PreCommencementTenderOffer" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_PreCommencementTenderOffer" order="39.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_PreCommencementIssuerTenderOffer" xlink:type="locator" xlink:label="dei_PreCommencementIssuerTenderOffer" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_PreCommencementIssuerTenderOffer" order="40.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_Security12bTitle" xlink:type="locator" xlink:label="dei_Security12bTitle" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_Security12bTitle" order="41.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_TradingSymbol" xlink:type="locator" xlink:label="dei_TradingSymbol" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_TradingSymbol" order="42.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_SecurityExchangeName" xlink:type="locator" xlink:label="dei_SecurityExchangeName" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_SecurityExchangeName" order="43.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityEmergingGrowthCompany" xlink:type="locator" xlink:label="dei_EntityEmergingGrowthCompany" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityEmergingGrowthCompany" order="44.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_AmendmentDescription" xlink:type="locator" xlink:label="dei_AmendmentDescription" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_AmendmentDescription" order="45.001" priority="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
</link:linkbase>
</XBRL>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>XML
<SEQUENCE>5
<FILENAME>R1.htm
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
<html>
<head>
<title></title>
<link rel="stylesheet" type="text/css" href="include/report.css">
<script type="text/javascript" src="Show.js">/* Do Not Remove This Comment */</script><script type="text/javascript">
							function toggleNextSibling (e) {
							if (e.nextSibling.style.display=='none') {
							e.nextSibling.style.display='block';
							} else { e.nextSibling.style.display='none'; }
							}</script>
</head>
<body>
<span style="display: none;">v3.23.3</span><table class="report" border="0" cellspacing="2" id="idm140444228211376">
<tr>
<th class="tl" colspan="1" rowspan="1"><div style="width: 200px;"><strong>Document and Entity Information<br></strong></div></th>
<th class="th"><div>Jun. 26, 2023</div></th>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_CoverAbstract', window );"><strong>Cover [Abstract]</strong></a></td>
<td class="text">&#160;<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_AmendmentFlag', window );">Amendment Flag</a></td>
<td class="text">true<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityCentralIndexKey', window );">Entity Central Index Key</a></td>
<td class="text">0000875045<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_DocumentType', window );">Document Type</a></td>
<td class="text">8-K/A<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_DocumentPeriodEndDate', window );">Document Period End Date</a></td>
<td class="text">Jun. 26,  2023<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityRegistrantName', window );">Entity Registrant Name</a></td>
<td class="text">Biogen Inc.<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityIncorporationStateCountryCode', window );">Entity Incorporation State Country Code</a></td>
<td class="text">DE<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityFileNumber', window );">Entity File Number</a></td>
<td class="text">0-19311<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityTaxIdentificationNumber', window );">Entity Tax Identification Number</a></td>
<td class="text">33-0112644<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityAddressAddressLine1', window );">Entity Address, Address Line One</a></td>
<td class="text">225 Binney Street<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityAddressCityOrTown', window );">Entity Address, City or Town</a></td>
<td class="text">Cambridge<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityAddressStateOrProvince', window );">Entity Address, State or Province</a></td>
<td class="text">MA<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityAddressPostalZipCode', window );">Entity Address, Postal Zip Code</a></td>
<td class="text">02142<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_CityAreaCode', window );">City Area Code</a></td>
<td class="text">(617)<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_LocalPhoneNumber', window );">Local Phone Number</a></td>
<td class="text">679-2000<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_WrittenCommunications', window );">Written Communications</a></td>
<td class="text">false<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_SolicitingMaterial', window );">Soliciting Material</a></td>
<td class="text">false<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_PreCommencementTenderOffer', window );">Pre Commencement Tender Offer</a></td>
<td class="text">false<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_PreCommencementIssuerTenderOffer', window );">Pre Commencement Issuer Tender Offer</a></td>
<td class="text">false<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_Security12bTitle', window );">Security 12b Title</a></td>
<td class="text">Common Stock, $0.0005 par value<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_TradingSymbol', window );">Trading Symbol</a></td>
<td class="text">BIIB<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_SecurityExchangeName', window );">Security Exchange Name</a></td>
<td class="text">NASDAQ<span></span>
</td>
</tr>
<tr class="re">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_EntityEmergingGrowthCompany', window );">Entity Emerging Growth Company</a></td>
<td class="text">false<span></span>
</td>
</tr>
<tr class="ro">
<td class="pl" style="border-bottom: 0px;" valign="top"><a class="a" href="javascript:void(0);" onclick="Show.showAR( this, 'defref_dei_AmendmentDescription', window );">Amendment Description</a></td>
<td class="text">This Current Report on Form 8-K/A (this &#8220;Amendment&#8221;) amends the Current Report on Form 8-K of Biogen Inc. (the &#8220;Company&#8221;) filed with the U.S. Securities and Exchange Commission on June&#160;29, 2023 (the &#8220;Original Form 8-K&#8221;). The Original Form 8-K reported the final voting results of the Company&#8217;s 2023 Annual Meeting of Stockholders held on June&#160;26, 2023 (the &#8220;Annual Meeting&#8221;). The sole purpose of this Amendment is to disclose the Company&#8217;s decision regarding whether stockholder votes to approve the compensation of its named executive officers required by Section&#160;14A(a)(1) of the Securities Exchange Act of 1934 and Rule 14a-21(a) promulgated thereunder (the &#8220;Say-on-Pay Vote&#8221;) should be held every one, two or three years (the &#8220;Say-on-Frequency Proposal&#8221;). No other changes have been made to the Original Form 8-K.<span></span>
</td>
</tr>
</table>
<div style="display: none;">
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_AmendmentDescription">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Description of changes contained within amended document.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_AmendmentDescription</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:stringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_AmendmentFlag">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_AmendmentFlag</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:booleanItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_CityAreaCode">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Area code of city</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_CityAreaCode</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:normalizedStringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_CoverAbstract">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Cover page.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_CoverAbstract</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:stringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_DocumentPeriodEndDate">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period.  The format of the date is YYYY-MM-DD.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_DocumentPeriodEndDate</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:dateItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_DocumentType">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_DocumentType</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:submissionTypeItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityAddressAddressLine1">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Address Line 1 such as Attn, Building Name, Street Name</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityAddressAddressLine1</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:normalizedStringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityAddressCityOrTown">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Name of the City or Town</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityAddressCityOrTown</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:normalizedStringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityAddressPostalZipCode">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Code for the postal or zip code</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityAddressPostalZipCode</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:normalizedStringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityAddressStateOrProvince">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Name of the state or province.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityAddressStateOrProvince</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:stateOrProvinceItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityCentralIndexKey">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 12<br> -Subsection b-2<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityCentralIndexKey</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:centralIndexKeyItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityEmergingGrowthCompany">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Indicate if registrant meets the emerging growth company criteria.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 12<br> -Subsection b-2<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityEmergingGrowthCompany</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:booleanItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityFileNumber">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityFileNumber</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:fileNumberItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityIncorporationStateCountryCode">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Two-character EDGAR code representing the state or country of incorporation.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityIncorporationStateCountryCode</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:edgarStateCountryItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityRegistrantName">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 12<br> -Subsection b-2<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityRegistrantName</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:normalizedStringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_EntityTaxIdentificationNumber">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 12<br> -Subsection b-2<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_EntityTaxIdentificationNumber</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:employerIdItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_LocalPhoneNumber">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Local phone number for entity.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_LocalPhoneNumber</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:normalizedStringItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_PreCommencementIssuerTenderOffer">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 13e<br> -Subsection 4c<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_PreCommencementIssuerTenderOffer</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:booleanItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_PreCommencementTenderOffer">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 14d<br> -Subsection 2b<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_PreCommencementTenderOffer</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:booleanItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_Security12bTitle">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Title of a 12(b) registered security.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 12<br> -Subsection b<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_Security12bTitle</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:securityTitleItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_SecurityExchangeName">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Name of the Exchange on which a security is registered.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Number 240<br> -Section 12<br> -Subsection d1-1<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_SecurityExchangeName</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:edgarExchangeCodeItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_SolicitingMaterial">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Exchange Act<br> -Section 14a<br> -Number 240<br> -Subsection 12<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_SolicitingMaterial</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:booleanItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_TradingSymbol">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Trading symbol of an instrument as listed on an exchange.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>No definition available.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_TradingSymbol</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>dei:tradingSymbolItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" class="authRefData" style="display: none;" id="defref_dei_WrittenCommunications">
<tr><td class="hide"><a style="color: white;" href="javascript:void(0);" onclick="Show.hideAR();">X</a></td></tr>
<tr><td><div class="body" style="padding: 2px;">
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">- Definition</a><div><p>Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.</p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ References</a><div style="display: none;"><p>Reference 1: http://www.xbrl.org/2003/role/presentationRef<br> -Publisher SEC<br> -Name Securities Act<br> -Number 230<br> -Section 425<br></p></div>
<a href="javascript:void(0);" onclick="Show.toggleNext( this );">+ Details</a><div style="display: none;"><table border="0" cellpadding="0" cellspacing="0">
<tr>
<td><strong> Name:</strong></td>
<td style="white-space:nowrap;">dei_WrittenCommunications</td>
</tr>
<tr>
<td style="padding-right: 4px;white-space:nowrap;"><strong> Namespace Prefix:</strong></td>
<td>dei_</td>
</tr>
<tr>
<td><strong> Data Type:</strong></td>
<td>xbrli:booleanItemType</td>
</tr>
<tr>
<td><strong> Balance Type:</strong></td>
<td>na</td>
</tr>
<tr>
<td><strong> Period Type:</strong></td>
<td>duration</td>
</tr>
</table></div>
</div></td></tr>
</table>
</div>
</body>
</html>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>XML
<SEQUENCE>6
<FILENAME>d534386d8ka_htm.xml
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
<XML>
<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2022"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="biib-20230626.xsd" xlink:type="simple"/>
    <context id="duration_2023-06-26_to_2023-06-26">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000875045</identifier>
        </entity>
        <period>
            <startDate>2023-06-26</startDate>
            <endDate>2023-06-26</endDate>
        </period>
    </context>
    <dei:AmendmentFlag contextRef="duration_2023-06-26_to_2023-06-26">true</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="duration_2023-06-26_to_2023-06-26"
      id="Hidden_dei_EntityCentralIndexKey">0000875045</dei:EntityCentralIndexKey>
    <dei:DocumentType contextRef="duration_2023-06-26_to_2023-06-26">8-K/A</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="duration_2023-06-26_to_2023-06-26">2023-06-26</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName contextRef="duration_2023-06-26_to_2023-06-26">Biogen Inc.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode contextRef="duration_2023-06-26_to_2023-06-26">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber contextRef="duration_2023-06-26_to_2023-06-26">0-19311</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber contextRef="duration_2023-06-26_to_2023-06-26">33-0112644</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1 contextRef="duration_2023-06-26_to_2023-06-26">225 Binney Street</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown contextRef="duration_2023-06-26_to_2023-06-26">Cambridge</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince contextRef="duration_2023-06-26_to_2023-06-26">MA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode contextRef="duration_2023-06-26_to_2023-06-26">02142</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode contextRef="duration_2023-06-26_to_2023-06-26">(617)</dei:CityAreaCode>
    <dei:LocalPhoneNumber contextRef="duration_2023-06-26_to_2023-06-26">679-2000</dei:LocalPhoneNumber>
    <dei:WrittenCommunications contextRef="duration_2023-06-26_to_2023-06-26">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial contextRef="duration_2023-06-26_to_2023-06-26">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer contextRef="duration_2023-06-26_to_2023-06-26">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer contextRef="duration_2023-06-26_to_2023-06-26">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle contextRef="duration_2023-06-26_to_2023-06-26">Common Stock, $0.0005 par value</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="duration_2023-06-26_to_2023-06-26">BIIB</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="duration_2023-06-26_to_2023-06-26">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany contextRef="duration_2023-06-26_to_2023-06-26">false</dei:EntityEmergingGrowthCompany>
    <dei:AmendmentDescription contextRef="duration_2023-06-26_to_2023-06-26">This Current Report on Form 8-K/A (this &#x201c;Amendment&#x201d;) amends the Current Report on Form 8-K of Biogen Inc. (the &#x201c;Company&#x201d;) filed with the U.S. Securities and Exchange Commission on June&#160;29, 2023 (the &#x201c;Original Form 8-K&#x201d;). The Original Form 8-K reported the final voting results of the Company&#x2019;s 2023 Annual Meeting of Stockholders held on June&#160;26, 2023 (the &#x201c;Annual Meeting&#x201d;). The sole purpose of this Amendment is to disclose the Company&#x2019;s decision regarding whether stockholder votes to approve the compensation of its named executive officers required by Section&#160;14A(a)(1) of the Securities Exchange Act of 1934 and Rule 14a-21(a) promulgated thereunder (the &#x201c;Say-on-Pay Vote&#x201d;) should be held every one, two or three years (the &#x201c;Say-on-Frequency Proposal&#x201d;). No other changes have been made to the Original Form 8-K.</dei:AmendmentDescription>
</xbrl>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EXCEL
<SEQUENCE>7
<FILENAME>Financial_Report.xlsx
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
begin 644 Financial_Report.xlsx
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M=]W3CHG&K=!X#;[Q3X?#KHG&J]!TZVDF)_VN:Z3I%FA"1N/K>A(5M>5 TR
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M!Z.:60F]A%9JGZJ'-#ZH'C(*!?&Y'C[E>G@*-Y;&O%"N@GL!_]':-\*K^(+
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MU4#E/]O4#6CV#30<D05>,9FV-J/D3@H\W/[O#;#"Q([A[8N_ 5!+ P04
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M(SF>FJC,M,2O',?IT8T(<G2R)BP-R6VJN5Z3^[2(-GKMLJ-Q$M.U$VP KPM
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MQF\ ;,RP2MQ]MS97YY\;4('DV;YC8P/.<\05F>12&J@GP*)3$TPZ<_0F]AA
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MQSC,H8@'O  >L;!*.2%Z)4R)J2.LL<D:&!I1 WAG#,-M:&UJ48P#BZL0/2*
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MPS ,0'_%T)XP!] AB#-E\18$^0%6H@_8$@6*19V_K]JE<9 +&7D]/!+<'FE
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M%S?W1:[-XPFNWPQP>'3^ 5!+ P04    "  ZBSQ799!YDAD!  #/ P  $P
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MKP   &1O8U!R;W!S+V-O<F4N>&UL4$L! A0#%     @ .HL\5YE<G",0!@
MG"<  !,              ( !S0$  'AL+W1H96UE+W1H96UE,2YX;6Q02P$"
M% ,4    "  ZBSQ72]5B5NT%  "<%   &               @($."   >&PO
M=V]R:W-H965T<R]S:&5E=#$N>&UL4$L! A0#%     @ .HL\5Y^@&_"Q @
MX@P   T              ( !,0X  'AL+W-T>6QE<RYX;6Q02P$"% ,4
M"  ZBSQ7EXJ[',     3 @  "P              @ $-$0  7W)E;',O+G)E
M;'-02P$"% ,4    "  ZBSQ7'#AEZC\!   \ @  #P              @ 'V
M$0  >&PO=V]R:V)O;VLN>&UL4$L! A0#%     @ .HL\5R0>FZ*M    ^ $
M !H              ( !8A,  'AL+U]R96QS+W=O<FMB;V]K+GAM;"YR96QS
M4$L! A0#%     @ .HL\5V60>9(9 0  SP,  !,              ( !1Q0
J %M#;VYT96YT7U1Y<&5S72YX;6Q02P4&      D "0 ^ @  D14

end
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>XML
<SEQUENCE>8
<FILENAME>Show.js
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
// Edgar(tm) Renderer was created by staff of the U.S. Securities and Exchange Commission.  Data and content created by government employees within the scope of their employment are not subject to domestic copyright protection. 17 U.S.C. 105.
var Show={};Show.LastAR=null,Show.showAR=function(a,r,w){if(Show.LastAR)Show.hideAR();var e=a;while(e&&e.nodeName!='TABLE')e=e.nextSibling;if(!e||e.nodeName!='TABLE'){var ref=((window)?w.document:document).getElementById(r);if(ref){e=ref.cloneNode(!0);
e.removeAttribute('id');a.parentNode.appendChild(e)}}
if(e)e.style.display='block';Show.LastAR=e};Show.hideAR=function(){Show.LastAR.style.display='none'};Show.toggleNext=function(a){var e=a;while(e.nodeName!='DIV')e=e.nextSibling;if(!e.style){}else if(!e.style.display){}else{var d,p_;if(e.style.display=='none'){d='block';p='-'}else{d='none';p='+'}
e.style.display=d;if(a.textContent){a.textContent=p+a.textContent.substring(1)}else{a.innerText=p+a.innerText.substring(1)}}}
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>XML
<SEQUENCE>9
<FILENAME>report.css
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
/* Updated 2009-11-04 */
/* v2.2.0.24 */

/* DefRef Styles */
..report table.authRefData{
	background-color: #def;
	border: 2px solid #2F4497;
	font-size: 1em;
	position: absolute;
}

..report table.authRefData a {
	display: block;
	font-weight: bold;
}

..report table.authRefData p {
	margin-top: 0px;
}

..report table.authRefData .hide {
	background-color: #2F4497;
	padding: 1px 3px 0px 0px;
	text-align: right;
}

..report table.authRefData .hide a:hover {
	background-color: #2F4497;
}

..report table.authRefData .body {
	height: 150px;
	overflow: auto;
	width: 400px;
}

..report table.authRefData table{
	font-size: 1em;
}

/* Report Styles */
..pl a, .pl a:visited {
	color: black;
	text-decoration: none;
}

/* table */
..report {
	background-color: white;
	border: 2px solid #acf;
	clear: both;
	color: black;
	font: normal 8pt Helvetica, Arial, san-serif;
	margin-bottom: 2em;
}

..report hr {
	border: 1px solid #acf;
}

/* Top labels */
..report th {
	background-color: #acf;
	color: black;
	font-weight: bold;
	text-align: center;
}

..report th.void	{
	background-color: transparent;
	color: #000000;
	font: bold 10pt Helvetica, Arial, san-serif;
	text-align: left;
}

..report .pl {
	text-align: left;
	vertical-align: top;
	white-space: normal;
	width: 200px;
	white-space: normal; /* word-wrap: break-word; */
}

..report td.pl a.a {
	cursor: pointer;
	display: block;
	width: 200px;
	overflow: hidden;
}

..report td.pl div.a {
	width: 200px;
}

..report td.pl a:hover {
	background-color: #ffc;
}

/* Header rows... */
..report tr.rh {
	background-color: #acf;
	color: black;
	font-weight: bold;
}

/* Calendars... */
..report .rc {
	background-color: #f0f0f0;
}

/* Even rows... */
..report .re, .report .reu {
	background-color: #def;
}

..report .reu td {
	border-bottom: 1px solid black;
}

/* Odd rows... */
..report .ro, .report .rou {
	background-color: white;
}

..report .rou td {
	border-bottom: 1px solid black;
}

..report .rou table td, .report .reu table td {
	border-bottom: 0px solid black;
}

/* styles for footnote marker */
..report .fn {
	white-space: nowrap;
}

/* styles for numeric types */
..report .num, .report .nump {
	text-align: right;
	white-space: nowrap;
}

..report .nump {
	padding-left: 2em;
}

..report .nump {
	padding: 0px 0.4em 0px 2em;
}

/* styles for text types */
..report .text {
	text-align: left;
	white-space: normal;
}

..report .text .big {
	margin-bottom: 1em;
	width: 17em;
}

..report .text .more {
	display: none;
}

..report .text .note {
	font-style: italic;
	font-weight: bold;
}

..report .text .small {
	width: 10em;
}

..report sup {
	font-style: italic;
}

..report .outerFootnotes {
	font-size: 1em;
}
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>XML
<SEQUENCE>10
<FILENAME>FilingSummary.xml
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
<XML>
<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.3</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>1</ContextCount>
  <ElementCount>23</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>0</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>0</UnitCount>
  <MyReports>
    <Report instance="d534386d8ka.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>biib-20230626.xsd</File>
    <File>biib-20230626_lab.xml</File>
    <File>biib-20230626_pre.xml</File>
    <File doctype="8-K/A" isOnlyDei="true" original="d534386d8ka.htm">d534386d8ka.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="23">http://xbrl.sec.gov/dei/2022</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>JSON
<SEQUENCE>12
<FILENAME>MetaLinks.json
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
{
 "version": "2.2",
 "instance": {
  "d534386d8ka.htm": {
   "nsprefix": "biib",
   "nsuri": "http://www.biogenidec.com/20230626",
   "dts": {
    "schema": {
     "local": [
      "biib-20230626.xsd"
     ],
     "remote": [
      "http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xl-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xlink-2003-12-31.xsd",
      "http://www.xbrl.org/2005/xbrldt-2005.xsd",
      "http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd",
      "http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd",
      "https://www.xbrl.org/dtr/type/2020-01-21/types.xsd",
      "https://xbrl.sec.gov/dei/2022/dei-2022.xsd",
      "https://xbrl.sec.gov/naics/2022/naics-2022.xsd"
     ]
    },
    "labelLink": {
     "local": [
      "biib-20230626_lab.xml"
     ]
    },
    "presentationLink": {
     "local": [
      "biib-20230626_pre.xml"
     ]
    },
    "inline": {
     "local": [
      "d534386d8ka.htm"
     ]
    }
   },
   "keyStandard": 23,
   "keyCustom": 0,
   "axisStandard": 0,
   "axisCustom": 0,
   "memberStandard": 0,
   "memberCustom": 0,
   "hidden": {
    "total": 2,
    "http://xbrl.sec.gov/dei/2022": 2
   },
   "contextCount": 1,
   "entityCount": 1,
   "segmentCount": 0,
   "elementCount": 24,
   "unitCount": 0,
   "baseTaxonomies": {
    "http://xbrl.sec.gov/dei/2022": 23
   },
   "report": {
    "R1": {
     "role": "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation",
     "longName": "100000 - Document - Document and Entity Information",
     "shortName": "Document and Entity Information",
     "isDefault": "true",
     "groupType": "document",
     "subGroupType": "",
     "menuCat": "Cover",
     "order": "1",
     "firstAnchor": {
      "contextRef": "duration_2023-06-26_to_2023-06-26",
      "name": "dei:DocumentType",
      "unitRef": null,
      "xsiNil": "false",
      "lang": "en-US",
      "decimals": null,
      "ancestors": [
       "p",
       "div",
       "div",
       "body",
       "html"
      ],
      "reportCount": 1,
      "baseRef": "d534386d8ka.htm",
      "first": true,
      "unique": true
     },
     "uniqueAnchor": {
      "contextRef": "duration_2023-06-26_to_2023-06-26",
      "name": "dei:DocumentType",
      "unitRef": null,
      "xsiNil": "false",
      "lang": "en-US",
      "decimals": null,
      "ancestors": [
       "p",
       "div",
       "div",
       "body",
       "html"
      ],
      "reportCount": 1,
      "baseRef": "d534386d8ka.htm",
      "first": true,
      "unique": true
     }
    }
   },
   "tag": {
    "dei_SolicitingMaterial": {
     "xbrltype": "booleanItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "SolicitingMaterial",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Soliciting Material",
        "terseLabel": "Soliciting Material",
        "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act."
       }
      }
     },
     "auth_ref": [
      "r5"
     ]
    },
    "dei_EntityTaxIdentificationNumber": {
     "xbrltype": "employerIdItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityTaxIdentificationNumber",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Tax Identification Number",
        "terseLabel": "Entity Tax Identification Number",
        "documentation": "The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS."
       }
      }
     },
     "auth_ref": [
      "r1"
     ]
    },
    "dei_Security12bTitle": {
     "xbrltype": "securityTitleItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "Security12bTitle",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Security 12b Title",
        "terseLabel": "Security 12b Title",
        "documentation": "Title of a 12(b) registered security."
       }
      }
     },
     "auth_ref": [
      "r0"
     ]
    },
    "dei_EntityIncorporationStateCountryCode": {
     "xbrltype": "edgarStateCountryItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityIncorporationStateCountryCode",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Incorporation State Country Code",
        "terseLabel": "Entity Incorporation State Country Code",
        "documentation": "Two-character EDGAR code representing the state or country of incorporation."
       }
      }
     },
     "auth_ref": []
    },
    "dei_PreCommencementIssuerTenderOffer": {
     "xbrltype": "booleanItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "PreCommencementIssuerTenderOffer",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Pre Commencement Issuer Tender Offer",
        "terseLabel": "Pre Commencement Issuer Tender Offer",
        "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act."
       }
      }
     },
     "auth_ref": [
      "r3"
     ]
    },
    "dei_EntityFileNumber": {
     "xbrltype": "fileNumberItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityFileNumber",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity File Number",
        "terseLabel": "Entity File Number",
        "documentation": "Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen."
       }
      }
     },
     "auth_ref": []
    },
    "dei_SecurityExchangeName": {
     "xbrltype": "edgarExchangeCodeItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "SecurityExchangeName",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Security Exchange Name",
        "terseLabel": "Security Exchange Name",
        "documentation": "Name of the Exchange on which a security is registered."
       }
      }
     },
     "auth_ref": [
      "r2"
     ]
    },
    "dei_EntityAddressAddressLine1": {
     "xbrltype": "normalizedStringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityAddressAddressLine1",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Address, Address Line One",
        "terseLabel": "Entity Address, Address Line One",
        "documentation": "Address Line 1 such as Attn, Building Name, Street Name"
       }
      }
     },
     "auth_ref": []
    },
    "dei_DocumentType": {
     "xbrltype": "submissionTypeItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "DocumentType",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Document Type",
        "terseLabel": "Document Type",
        "documentation": "The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'."
       }
      }
     },
     "auth_ref": []
    },
    "dei_EntityAddressCityOrTown": {
     "xbrltype": "normalizedStringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityAddressCityOrTown",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Address, City or Town",
        "terseLabel": "Entity Address, City or Town",
        "documentation": "Name of the City or Town"
       }
      }
     },
     "auth_ref": []
    },
    "dei_CityAreaCode": {
     "xbrltype": "normalizedStringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "CityAreaCode",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "City Area Code",
        "terseLabel": "City Area Code",
        "documentation": "Area code of city"
       }
      }
     },
     "auth_ref": []
    },
    "dei_EntityAddressStateOrProvince": {
     "xbrltype": "stateOrProvinceItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityAddressStateOrProvince",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Address, State or Province",
        "terseLabel": "Entity Address, State or Province",
        "documentation": "Name of the state or province."
       }
      }
     },
     "auth_ref": []
    },
    "dei_PreCommencementTenderOffer": {
     "xbrltype": "booleanItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "PreCommencementTenderOffer",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Pre Commencement Tender Offer",
        "terseLabel": "Pre Commencement Tender Offer",
        "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act."
       }
      }
     },
     "auth_ref": [
      "r4"
     ]
    },
    "dei_AmendmentFlag": {
     "xbrltype": "booleanItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "AmendmentFlag",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Amendment Flag",
        "terseLabel": "Amendment Flag",
        "documentation": "Boolean flag that is true when the XBRL content amends previously-filed or accepted submission."
       }
      }
     },
     "auth_ref": []
    },
    "dei_LocalPhoneNumber": {
     "xbrltype": "normalizedStringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "LocalPhoneNumber",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Local Phone Number",
        "terseLabel": "Local Phone Number",
        "documentation": "Local phone number for entity."
       }
      }
     },
     "auth_ref": []
    },
    "dei_AmendmentDescription": {
     "xbrltype": "stringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "AmendmentDescription",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Amendment Description",
        "terseLabel": "Amendment Description",
        "documentation": "Description of changes contained within amended document."
       }
      }
     },
     "auth_ref": []
    },
    "dei_EntityRegistrantName": {
     "xbrltype": "normalizedStringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityRegistrantName",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Registrant Name",
        "terseLabel": "Entity Registrant Name",
        "documentation": "The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC."
       }
      }
     },
     "auth_ref": [
      "r1"
     ]
    },
    "dei_EntityAddressPostalZipCode": {
     "xbrltype": "normalizedStringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityAddressPostalZipCode",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Address, Postal Zip Code",
        "terseLabel": "Entity Address, Postal Zip Code",
        "documentation": "Code for the postal or zip code"
       }
      }
     },
     "auth_ref": []
    },
    "dei_TradingSymbol": {
     "xbrltype": "tradingSymbolItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "TradingSymbol",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Trading Symbol",
        "terseLabel": "Trading Symbol",
        "documentation": "Trading symbol of an instrument as listed on an exchange."
       }
      }
     },
     "auth_ref": []
    },
    "dei_DocumentPeriodEndDate": {
     "xbrltype": "dateItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "DocumentPeriodEndDate",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Document Period End Date",
        "terseLabel": "Document Period End Date",
        "documentation": "For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period.  The format of the date is YYYY-MM-DD."
       }
      }
     },
     "auth_ref": []
    },
    "dei_CoverAbstract": {
     "xbrltype": "stringItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "CoverAbstract",
     "lang": {
      "en-us": {
       "role": {
        "label": "Cover [Abstract]",
        "terseLabel": "Cover [Abstract]",
        "documentation": "Cover page."
       }
      }
     },
     "auth_ref": []
    },
    "dei_EntityEmergingGrowthCompany": {
     "xbrltype": "booleanItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityEmergingGrowthCompany",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Emerging Growth Company",
        "terseLabel": "Entity Emerging Growth Company",
        "documentation": "Indicate if registrant meets the emerging growth company criteria."
       }
      }
     },
     "auth_ref": [
      "r1"
     ]
    },
    "dei_EntityCentralIndexKey": {
     "xbrltype": "centralIndexKeyItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "EntityCentralIndexKey",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Entity Central Index Key",
        "terseLabel": "Entity Central Index Key",
        "documentation": "A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK."
       }
      }
     },
     "auth_ref": [
      "r1"
     ]
    },
    "dei_WrittenCommunications": {
     "xbrltype": "booleanItemType",
     "nsuri": "http://xbrl.sec.gov/dei/2022",
     "localname": "WrittenCommunications",
     "presentation": [
      "http://www.biogenidec.com//20230626/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Written Communications",
        "terseLabel": "Written Communications",
        "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act."
       }
      }
     },
     "auth_ref": [
      "r6"
     ]
    }
   }
  }
 },
 "std_ref": {
  "r0": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Exchange Act",
   "Number": "240",
   "Section": "12",
   "Subsection": "b"
  },
  "r1": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Exchange Act",
   "Number": "240",
   "Section": "12",
   "Subsection": "b-2"
  },
  "r2": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Exchange Act",
   "Number": "240",
   "Section": "12",
   "Subsection": "d1-1"
  },
  "r3": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Exchange Act",
   "Number": "240",
   "Section": "13e",
   "Subsection": "4c"
  },
  "r4": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Exchange Act",
   "Number": "240",
   "Section": "14d",
   "Subsection": "2b"
  },
  "r5": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Exchange Act",
   "Section": "14a",
   "Number": "240",
   "Subsection": "12"
  },
  "r6": {
   "role": "http://www.xbrl.org/2003/role/presentationRef",
   "Publisher": "SEC",
   "Name": "Securities Act",
   "Number": "230",
   "Section": "425"
  }
 }
}
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>ZIP
<SEQUENCE>13
<FILENAME>0001193125-23-245816-xbrl.zip
<DESCRIPTION>IDEA: XBRL DOCUMENT
<TEXT>
begin 644 0001193125-23-245816-xbrl.zip
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MMN/:VZYDW2"SS4EN;_H3WUPU&X=^_@902P,$%     @ .HL\5TD;'F^.!@
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M9 .7E/DLH'X$=T7+;^"*!7TXBR+XHM.DZE,2\4#"?JX:4?;O6/\UT]W#ZU<
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M&EF?"NN(N+K$CABVV-Q99!E)SB*6,3%[P!]CQ8RUTYB5*:L+K,RMI>7.BLE
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M>SM>5WH=9+[2G2 T0Z,11"QXIQ]F?*FCK+ \V_SH6O7)=*UZ0L&S%I$6%R1
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H#P  9#4S-#,X-F0X:V$N:'1M4$L%!@     $  0  @$  %H>      $!

end
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
