<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>2397</ContextCount>
  <ElementCount>940</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>620</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>50</UnitCount>
  <MyReports>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Document - Audit Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/AuditInformation</Role>
      <ShortName>Audit Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952151 - Statement - Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofOperations</Role>
      <ShortName>Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952152 - Statement - Consolidated Statements of Operations (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofOperationsParenthetical</Role>
      <ShortName>Consolidated Statements of Operations (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952153 - Statement - Consolidated Statements of Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofOtherComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Other Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952154 - Statement - Consolidated Statements of Financial Position</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofFinancialPosition</Role>
      <ShortName>Consolidated Statements of Financial Position</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952155 - Statement - Consolidated Statements of Financial Position (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofFinancialPositionParenthetical</Role>
      <ShortName>Consolidated Statements of Financial Position (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952156 - Statement - Consolidated Statements of Changes In Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofChangesInEquity</Role>
      <ShortName>Consolidated Statements of Changes In Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952157 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952158 - Statement - Consolidated Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ConsolidatedStatementsofCashFlowsParenthetical</Role>
      <ShortName>Consolidated Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - ACCOUNTING PRINCIPLES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ACCOUNTINGPRINCIPLES</Role>
      <ShortName>ACCOUNTING PRINCIPLES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - SCOPE OF CONSOLIDATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATION</Role>
      <ShortName>SCOPE OF CONSOLIDATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - SEGMENT REPORTING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTING</Role>
      <ShortName>SEGMENT REPORTING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - OPERATING DATA</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATA</Role>
      <ShortName>OPERATING DATA</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETS</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTS</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - LEASES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASES</Role>
      <ShortName>LEASES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITS</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTS</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952171 - Disclosure - EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITY</Role>
      <ShortName>EQUITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9952172 - Disclosure - RELATED PARTIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/RELATEDPARTIES</Role>
      <ShortName>RELATED PARTIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995447 - Disclosure - Insider Trading Policies and Procedures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc</Role>
      <ShortName>Insider Trading Policies and Procedures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995550 - Disclosure - Cybersecurity Risk Management and Strategy Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/cyd/role/CybersecurityRiskManagementAndStrategyDisclosure</Role>
      <ShortName>Cybersecurity Risk Management and Strategy Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - ACCOUNTING PRINCIPLES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ACCOUNTINGPRINCIPLESPolicies</Role>
      <ShortName>ACCOUNTING PRINCIPLES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - SCOPE OF CONSOLIDATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONTables</Role>
      <ShortName>SCOPE OF CONSOLIDATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATION</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - SEGMENT REPORTING (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGTables</Role>
      <ShortName>SEGMENT REPORTING (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/SEGMENTREPORTING</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - OPERATING DATA (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATATables</Role>
      <ShortName>OPERATING DATA (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/OPERATINGDATA</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSTables</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETS</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSTables</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTS</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - LEASES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASESTables</Role>
      <ShortName>LEASES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/LEASES</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSTables</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITS</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSTables</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTS</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - INCOME TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESTables</Role>
      <ShortName>INCOME TAXES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/INCOMETAXES</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - EQUITY (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYTables</Role>
      <ShortName>EQUITY (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/EQUITY</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - RELATED PARTIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/RELATEDPARTIESTables</Role>
      <ShortName>RELATED PARTIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://corporate.arcelormittal.com/role/RELATEDPARTIES</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - ACCOUNTING PRINCIPLES - Climate change disclosures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ACCOUNTINGPRINCIPLESClimatechangedisclosuresDetails</Role>
      <ShortName>ACCOUNTING PRINCIPLES - Climate change disclosures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - ACCOUNTING PRINCIPLES - Situation in Ukraine and collateral consequences (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/ACCOUNTINGPRINCIPLESSituationinUkraineandcollateralconsequencesDetails</Role>
      <ShortName>ACCOUNTING PRINCIPLES - Situation in Ukraine and collateral consequences (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - SCOPE OF CONSOLIDATION - List of Subsidiaries (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONListofSubsidiariesDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - List of Subsidiaries (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - SCOPE OF CONSOLIDATION - Translation of Financial Statements Denominated in Foreign Currency (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONTranslationofFinancialStatementsDenominatedinForeignCurrencyDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Translation of Financial Statements Denominated in Foreign Currency (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - SCOPE OF CONSOLIDATION - Acquisitions Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONAcquisitionsNarrativeDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Acquisitions Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - SCOPE OF CONSOLIDATION - Schedule of Assets Acquired and Liabilities Assumed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONScheduleofAssetsAcquiredandLiabilitiesAssumedDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Schedule of Assets Acquired and Liabilities Assumed (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - SCOPE OF CONSOLIDATION - Divestments Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONDivestmentsNarrativeDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Divestments Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - SCOPE OF CONSOLIDATION - Schedule of Assets and Liabilities Held For Sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONScheduleofAssetsandLiabilitiesHeldForSaleDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Schedule of Assets and Liabilities Held For Sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - SCOPE OF CONSOLIDATION - Summary of Divestments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONSummaryofDivestmentsDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Summary of Divestments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - SCOPE OF CONSOLIDATION - Investment in Associates and Joint Arrangements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONInvestmentinAssociatesandJointArrangementsDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Investment in Associates and Joint Arrangements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - SCOPE OF CONSOLIDATION - Summary of Joint Ventures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONSummaryofJointVenturesDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Summary of Joint Ventures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - SCOPE OF CONSOLIDATION - Joint Ventures Narrative AMNS India (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONJointVenturesNarrativeAMNSIndiaDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Joint Ventures Narrative AMNS India (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - SCOPE OF CONSOLIDATION - Joint Ventures Narrative Other (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONJointVenturesNarrativeOtherDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Joint Ventures Narrative Other (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - SCOPE OF CONSOLIDATION - Summary of Associates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONSummaryofAssociatesDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Summary of Associates (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - SCOPE OF CONSOLIDATION - Associates Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONAssociatesNarrativeDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Associates Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - SCOPE OF CONSOLIDATION - Other Associates and Joint Ventures that are not Individually Material (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONOtherAssociatesandJointVenturesthatarenotIndividuallyMaterialDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Other Associates and Joint Ventures that are not Individually Material (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - SCOPE OF CONSOLIDATION - Investments in Joint Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONInvestmentsinJointOperationsDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Investments in Joint Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - SCOPE OF CONSOLIDATION - Schedule Of Other Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONScheduleOfOtherInvestmentsDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Schedule Of Other Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - SCOPE OF CONSOLIDATION - Other Investments Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONOtherInvestmentsNarrativeDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Other Investments Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - SCOPE OF CONSOLIDATION - Income (Loss) from Investments in Associates, Joint Ventures and Other Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONIncomeLossfromInvestmentsinAssociatesJointVenturesandOtherInvestmentsDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Income (Loss) from Investments in Associates, Joint Ventures and Other Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - SCOPE OF CONSOLIDATION - Impairment of Associates and Joint Ventures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SCOPEOFCONSOLIDATIONImpairmentofAssociatesandJointVenturesDetails</Role>
      <ShortName>SCOPE OF CONSOLIDATION - Impairment of Associates and Joint Ventures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - SEGMENT REPORTING - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGNarrativeDetails</Role>
      <ShortName>SEGMENT REPORTING - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - SEGMENT REPORTING - Reportable Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGReportableSegmentsDetails</Role>
      <ShortName>SEGMENT REPORTING - Reportable Segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - SEGMENT REPORTING - Sales by Geographical Area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGSalesbyGeographicalAreaDetails</Role>
      <ShortName>SEGMENT REPORTING - Sales by Geographical Area (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - SEGMENT REPORTING - Non-current Assets by Geographical Area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGNoncurrentAssetsbyGeographicalAreaDetails</Role>
      <ShortName>SEGMENT REPORTING - Non-current Assets by Geographical Area (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - SEGMENT REPORTING - Sales by Type of Products (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGSalesbyTypeofProductsDetails</Role>
      <ShortName>SEGMENT REPORTING - Sales by Type of Products (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - SEGMENT REPORTING - Disaggregated Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/SEGMENTREPORTINGDisaggregatedRevenueDetails</Role>
      <ShortName>SEGMENT REPORTING - Disaggregated Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - OPERATING DATA - Revenue Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATARevenueNarrativeDetails</Role>
      <ShortName>OPERATING DATA - Revenue Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9955551 - Disclosure - OPERATING DATA - Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATARevenueDetails</Role>
      <ShortName>OPERATING DATA - Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9955552 - Disclosure - OPERATING DATA - Schedule of Cost of Sales (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAScheduleofCostofSalesDetails</Role>
      <ShortName>OPERATING DATA - Schedule of Cost of Sales (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9955553 - Disclosure - OPERATING DATA - Trade Accounts Receivable and Other - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATATradeAccountsReceivableandOtherNarrativeDetails</Role>
      <ShortName>OPERATING DATA - Trade Accounts Receivable and Other - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9955554 - Disclosure - OPERATING DATA - Schedule of Trade Accounts Receivable and Allowance for Expected Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAScheduleofTradeAccountsReceivableandAllowanceforExpectedCreditLossesDetails</Role>
      <ShortName>OPERATING DATA - Schedule of Trade Accounts Receivable and Allowance for Expected Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9955555 - Disclosure - OPERATING DATA - Exposure to Credit Risk by Reportable Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAExposuretoCreditRiskbyReportableSegmentDetails</Role>
      <ShortName>OPERATING DATA - Exposure to Credit Risk by Reportable Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9955556 - Disclosure - OPERATING DATA - Aging of Trade Accounts Receivable (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAAgingofTradeAccountsReceivableDetails</Role>
      <ShortName>OPERATING DATA - Aging of Trade Accounts Receivable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9955557 - Disclosure - OPERATING DATA - Movement in the Allowance for Lifetime Expected Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAMovementintheAllowanceforLifetimeExpectedCreditLossesDetails</Role>
      <ShortName>OPERATING DATA - Movement in the Allowance for Lifetime Expected Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9955558 - Disclosure - OPERATING DATA - Inventories - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAInventoriesNarrativeDetails</Role>
      <ShortName>OPERATING DATA - Inventories - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9955559 - Disclosure - OPERATING DATA - Schedule of Inventories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAScheduleofInventoriesDetails</Role>
      <ShortName>OPERATING DATA - Schedule of Inventories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9955560 - Disclosure - OPERATING DATA - Movement in Inventory Reserve (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAMovementinInventoryReserveDetails</Role>
      <ShortName>OPERATING DATA - Movement in Inventory Reserve (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>9955561 - Disclosure - OPERATING DATA - Schedule of Prepaid Expenses and Other Current Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAScheduleofPrepaidExpensesandOtherCurrentAssetsDetails</Role>
      <ShortName>OPERATING DATA - Schedule of Prepaid Expenses and Other Current Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>9955562 - Disclosure - OPERATING DATA - Schedule of Other Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAScheduleofOtherAssetsDetails</Role>
      <ShortName>OPERATING DATA - Schedule of Other Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>9955563 - Disclosure - OPERATING DATA - Trade Accounts Payable and Other - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATATradeAccountsPayableandOtherNarrativeDetails</Role>
      <ShortName>OPERATING DATA - Trade Accounts Payable and Other - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>9955564 - Disclosure - OPERATING DATA - Schedule of Accrued Expenses and Other Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/OPERATINGDATAScheduleofAccruedExpensesandOtherLiabilitiesDetails</Role>
      <ShortName>OPERATING DATA - Schedule of Accrued Expenses and Other Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>9955565 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSGoodwillandIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>9955566 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSGoodwillandIntangibleAssetsNarrativeDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>9955567 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets, Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSGoodwillandIntangibleAssetsGoodwillDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets, Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>9955568 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets, Other Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSGoodwillandIntangibleAssetsOtherIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Goodwill and Intangible Assets, Other Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>9955569 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Property, Plant and Equipment and Biological Assets, Useful Lives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSPropertyPlantandEquipmentandBiologicalAssetsUsefulLivesDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Property, Plant and Equipment and Biological Assets, Useful Lives (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>9955570 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Property, Plant and Equipment and Biological Assets Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSPropertyPlantandEquipmentandBiologicalAssetsNarrativeDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Property, Plant and Equipment and Biological Assets Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>9955571 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Property, Plant and Equipment and Biological Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSPropertyPlantandEquipmentandBiologicalAssetsDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Property, Plant and Equipment and Biological Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>9955572 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Impairment of Intangible Assets, Including Goodwill, and Tangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSImpairmentofIntangibleAssetsIncludingGoodwillandTangibleAssetsDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Impairment of Intangible Assets, Including Goodwill, and Tangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>9955573 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Impairment of Intangible Assets, Including Goodwill, and Tangible Assets, Impairment Test of Goodwill and Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSImpairmentofIntangibleAssetsIncludingGoodwillandTangibleAssetsImpairmentTestofGoodwillandIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Impairment of Intangible Assets, Including Goodwill, and Tangible Assets, Impairment Test of Goodwill and Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>9955574 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Sensitivity on Impairment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSSensitivityonImpairmentDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Sensitivity on Impairment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>9955575 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Impairment test of PPE and Intangibles (excluding goodwill) Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSImpairmenttestofPPEandIntangiblesexcludinggoodwillNarrativeDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - Impairment test of PPE and Intangibles (excluding goodwill) Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>9955576 - Disclosure - GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - CGU impairment assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/GOODWILLINTANGIBLEANDTANGIBLEASSETSCGUimpairmentassumptionsDetails</Role>
      <ShortName>GOODWILL, INTANGIBLE AND TANGIBLE ASSETS - CGU impairment assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>9955577 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Summary of Assets and Liabilities Based on Categories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSSummaryofAssetsandLiabilitiesBasedonCategoriesDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Summary of Assets and Liabilities Based on Categories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>9955578 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Schedule of Assets and Liabilities at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSScheduleofAssetsandLiabilitiesatFairValueDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Schedule of Assets and Liabilities at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>9955579 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Short-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtShorttermDebtDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Short-term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>9955580 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtLongtermDebtDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Long-term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>9955581 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Long-Term Debt, Narrative Credit Facility and Bonds (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtLongTermDebtNarrativeCreditFacilityandBondsDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Long-Term Debt, Narrative Credit Facility and Bonds (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>9955582 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Interest Rate "Step-Up" (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtInterestRateStepUpDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Interest Rate "Step-Up" (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>9955583 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Long-Term Debt, Narrative EIB, Other Loans, Hedging (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtLongTermDebtNarrativeEIBOtherLoansHedgingDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Long-Term Debt, Narrative EIB, Other Loans, Hedging (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>9955584 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Maturities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtMaturitiesDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Maturities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>9955585 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Carrying Value and Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSGrossDebtCarryingValueandFairValueDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Gross Debt - Carrying Value and Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>9955586 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Schedule of Cash and Cash Equivalents and Restricted Cash (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSScheduleofCashandCashEquivalentsandRestrictedCashDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Schedule of Cash and Cash Equivalents and Restricted Cash (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>9955587 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Reconciliation of Liabilities Arising from Financing Activities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSReconciliationofLiabilitiesArisingfromFinancingActivitiesDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Reconciliation of Liabilities Arising from Financing Activities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>9955588 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Net Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSNetDebtDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Net Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>9955589 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Derivative Financial Instruments - Classified as Level 2 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSDerivativeFinancialInstrumentsClassifiedasLevel2Details</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Derivative Financial Instruments - Classified as Level 2 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>9955590 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Raw Materials, Freight, Energy Risks and Emission Rights (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyRawMaterialsFreightEnergyRisksandEmissionRightsDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Raw Materials, Freight, Energy Risks and Emission Rights (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>9955591 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Derivative Financial Instruments - Classified as Level 3 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSDerivativeFinancialInstrumentsClassifiedasLevel3Details</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Derivative Financial Instruments - Classified as Level 3 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>9955592 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Financing Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSFinancingCostsDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Financing Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>9955593 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Capital Management (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyCapitalManagementDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Capital Management (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>9955594 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Interest Rate Risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyInterestRateRiskDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Interest Rate Risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>9955595 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Foreign Currency Sensitivity Analysis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyForeignCurrencySensitivityAnalysisDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Foreign Currency Sensitivity Analysis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>9955596 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Liquidity Risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyLiquidityRiskDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Liquidity Risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>9955597 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Cash Flow Hedges (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyCashFlowHedgesDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Cash Flow Hedges (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>9955598 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Effect of Hedge Accounting, Cash Flow Hedges (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyEffectofHedgeAccountingCashFlowHedgesDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Effect of Hedge Accounting, Cash Flow Hedges (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>9955599 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Net Investment Hedges (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyNetInvestmentHedgesDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Net Investment Hedges (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>9955600 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Foreign Currency Sensitivity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyForeignCurrencySensitivityDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Foreign Currency Sensitivity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>114</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>9955601 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Cash Flow Sensitivity on Variable Rate Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicyCashFlowSensitivityonVariableRateInstrumentsDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Cash Flow Sensitivity on Variable Rate Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>9955602 - Disclosure - FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Sensitivity Analysis - Base Metals, Energy, Freight, Emissions Right (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/FINANCINGANDFINANCIALINSTRUMENTSRiskmanagementpolicySensitivityAnalysisBaseMetalsEnergyFreightEmissionsRightDetails</Role>
      <ShortName>FINANCING AND FINANCIAL INSTRUMENTS - Risk management policy - Sensitivity Analysis - Base Metals, Energy, Freight, Emissions Right (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>9955603 - Disclosure - LEASES - Right-of-use Assets, Depreciation and Impairment Charges (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASESRightofuseAssetsDepreciationandImpairmentChargesDetails</Role>
      <ShortName>LEASES - Right-of-use Assets, Depreciation and Impairment Charges (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>9955604 - Disclosure - LEASES - Maturity Analysis of Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASESMaturityAnalysisofLeaseLiabilitiesDetails</Role>
      <ShortName>LEASES - Maturity Analysis of Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>9955605 - Disclosure - LEASES - Potential Variable Lease Cash Outflows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASESPotentialVariableLeaseCashOutflowsDetails</Role>
      <ShortName>LEASES - Potential Variable Lease Cash Outflows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>9955606 - Disclosure - LEASES - Potential Addition/(Reduction) in Future Cash Flows From Extension Options and/or Termination Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASESPotentialAdditionReductioninFutureCashFlowsFromExtensionOptionsandorTerminationOptionsDetails</Role>
      <ShortName>LEASES - Potential Addition/(Reduction) in Future Cash Flows From Extension Options and/or Termination Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>9955607 - Disclosure - LEASES - Leases Not Yet Commenced (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/LEASESLeasesNotYetCommencedDetails</Role>
      <ShortName>LEASES - Leases Not Yet Commenced (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>9955608 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Employees and Key Management Personnel Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSEmployeesandKeyManagementPersonnelNarrativeDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Employees and Key Management Personnel Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>9955609 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Employees' Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSEmployeesCompensationDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Employees' Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>9955610 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Key Management Personnel's Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSKeyManagementPersonnelsCompensationDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Key Management Personnel's Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>124</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>9955611 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Deferred Employee Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSDeferredEmployeeBenefitsDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Deferred Employee Benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>125</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>9955612 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Deferred Employee Benefits - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSDeferredEmployeeBenefitsNarrativeDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Deferred Employee Benefits - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>126</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>9955613 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Reconciliation of Defined Benefit Obligation, Plan Assets and Statements of Financial Position (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSReconciliationofDefinedBenefitObligationPlanAssetsandStatementsofFinancialPositionDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Reconciliation of Defined Benefit Obligation, Plan Assets and Statements of Financial Position (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>127</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>9955614 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Net Periodic Pension Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSNetPeriodicPensionCostDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Net Periodic Pension Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>128</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>9955615 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Summary of Changes in the OPEB Obligation and Changes in Plan Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSSummaryofChangesintheOPEBObligationandChangesinPlanAssetsDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Summary of Changes in the OPEB Obligation and Changes in Plan Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>129</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>9955616 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Net Periodic Other Post-Employment Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSNetPeriodicOtherPostEmploymentCostDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Net Periodic Other Post-Employment Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>130</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>9955617 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Expenses Recognized in Income Statement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSExpensesRecognizedinIncomeStatementDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Expenses Recognized in Income Statement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>9955618 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Weighted Average Asset Allocation for the Funded Defined Benefit Pension Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSWeightedAverageAssetAllocationfortheFundedDefinedBenefitPensionPlansDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Weighted Average Asset Allocation for the Funded Defined Benefit Pension Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>132</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>9955619 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Target Asset Allocation for the Funded Defined Benefit Pension Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSTargetAssetAllocationfortheFundedDefinedBenefitPensionPlansDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Target Asset Allocation for the Funded Defined Benefit Pension Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>133</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>9955620 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Actuarial Assumptions for Defined Benefit Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSActuarialAssumptionsforDefinedBenefitPlansDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Actuarial Assumptions for Defined Benefit Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>134</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R135.htm</HtmlFileName>
      <LongName>9955621 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Healthcare Cost Trend Rate (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSHealthcareCostTrendRateDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Healthcare Cost Trend Rate (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>135</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R136.htm</HtmlFileName>
      <LongName>9955622 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Cash Contributions and Maturity Profile, Life Expectancy - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSCashContributionsandMaturityProfileLifeExpectancyNarrativeDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Cash Contributions and Maturity Profile, Life Expectancy - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>136</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R137.htm</HtmlFileName>
      <LongName>9955623 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Sensitivity to a Change of the Significant Actuarial Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSSensitivitytoaChangeoftheSignificantActuarialAssumptionsDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Sensitivity to a Change of the Significant Actuarial Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>137</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R138.htm</HtmlFileName>
      <LongName>9955624 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Share Based Payments - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSShareBasedPaymentsNarrativeDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Share Based Payments - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>138</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R139.htm</HtmlFileName>
      <LongName>9955625 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Terms and Conditions of Grants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSTermsandConditionsofGrantsDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Terms and Conditions of Grants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>139</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R140.htm</HtmlFileName>
      <LongName>9955626 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Summary of Share Unit Plans Outstanding (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSSummaryofShareUnitPlansOutstandingDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Summary of Share Unit Plans Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>140</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R141.htm</HtmlFileName>
      <LongName>9955627 - Disclosure - PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Share Unit Plan Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PERSONNELEXPENSESANDDEFERREDEMPLOYEEBENEFITSShareUnitPlanActivityDetails</Role>
      <ShortName>PERSONNEL EXPENSES AND DEFERRED EMPLOYEE BENEFITS - Share Unit Plan Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>141</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R142.htm</HtmlFileName>
      <LongName>9955628 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Provisions Overview (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSProvisionsOverviewDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Provisions Overview (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>142</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R143.htm</HtmlFileName>
      <LongName>9955629 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Provisions Overview - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSProvisionsOverviewNarrativeDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Provisions Overview - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>143</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R144.htm</HtmlFileName>
      <LongName>9955630 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Narrative Environmental Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSNarrativeEnvironmentalLiabilitiesDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Narrative Environmental Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>144</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R145.htm</HtmlFileName>
      <LongName>9955631 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Narrative Asset Retirement Obligation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSNarrativeAssetRetirementObligationDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Narrative Asset Retirement Obligation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>145</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R146.htm</HtmlFileName>
      <LongName>9955632 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Other Long-Term Obligations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSOtherLongTermObligationsDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Other Long-Term Obligations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>146</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R147.htm</HtmlFileName>
      <LongName>9955633 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Narrative Tax Claims (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSNarrativeTaxClaimsDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Narrative Tax Claims (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>147</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R148.htm</HtmlFileName>
      <LongName>9955634 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Competition and Antitrust Claims (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSCompetitionandAntitrustClaimsDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Competition and Antitrust Claims (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>148</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R149.htm</HtmlFileName>
      <LongName>9955635 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Other Legal Claims (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSOtherLegalClaimsDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Other Legal Claims (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>149</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R150.htm</HtmlFileName>
      <LongName>9955636 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Summary of Commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSSummaryofCommitmentsDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Summary of Commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>150</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R151.htm</HtmlFileName>
      <LongName>9955637 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Commitments - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSCommitmentsNarrativeDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Commitments - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>151</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R152.htm</HtmlFileName>
      <LongName>9955638 - Disclosure - PROVISIONS, CONTINGENCIES AND COMMITMENTS - Summary PPA Renewable Energy (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/PROVISIONSCONTINGENCIESANDCOMMITMENTSSummaryPPARenewableEnergyDetails</Role>
      <ShortName>PROVISIONS, CONTINGENCIES AND COMMITMENTS - Summary PPA Renewable Energy (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>152</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R153.htm</HtmlFileName>
      <LongName>9955639 - Disclosure - INCOME TAXES - Components of Income Tax Expense (Benefit) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESComponentsofIncomeTaxExpenseBenefitDetails</Role>
      <ShortName>INCOME TAXES - Components of Income Tax Expense (Benefit) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>153</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R154.htm</HtmlFileName>
      <LongName>9955640 - Disclosure - INCOME TAXES - Effective Income Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESEffectiveIncomeTaxRateReconciliationDetails</Role>
      <ShortName>INCOME TAXES - Effective Income Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>154</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R155.htm</HtmlFileName>
      <LongName>9955641 - Disclosure - INCOME TAXES - Narrative Income Tax expense (Benefit) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESNarrativeIncomeTaxexpenseBenefitDetails</Role>
      <ShortName>INCOME TAXES - Narrative Income Tax expense (Benefit) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>155</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R156.htm</HtmlFileName>
      <LongName>9955642 - Disclosure - INCOME TAXES - Permanent Items (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESPermanentItemsDetails</Role>
      <ShortName>INCOME TAXES - Permanent Items (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>156</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R157.htm</HtmlFileName>
      <LongName>9955643 - Disclosure - INCOME TAXES - Others (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESOthersDetails</Role>
      <ShortName>INCOME TAXES - Others (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>157</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R158.htm</HtmlFileName>
      <LongName>9955644 - Disclosure - INCOME TAXES - Income Tax Recorded Directly in Equity and Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESIncomeTaxRecordedDirectlyinEquityandOtherComprehensiveIncomeDetails</Role>
      <ShortName>INCOME TAXES - Income Tax Recorded Directly in Equity and Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>158</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R159.htm</HtmlFileName>
      <LongName>9955645 - Disclosure - INCOME TAXES - Origin of the Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESOriginoftheDeferredTaxAssetsandLiabilitiesDetails</Role>
      <ShortName>INCOME TAXES - Origin of the Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>159</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R160.htm</HtmlFileName>
      <LongName>9955646 - Disclosure - INCOME TAXES - Deferred Tax Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESDeferredTaxAssetsDetails</Role>
      <ShortName>INCOME TAXES - Deferred Tax Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>160</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R161.htm</HtmlFileName>
      <LongName>9955647 - Disclosure - INCOME TAXES - Narrative Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESNarrativeDeferredTaxAssetsandLiabilitiesDetails</Role>
      <ShortName>INCOME TAXES - Narrative Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>161</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R162.htm</HtmlFileName>
      <LongName>9955648 - Disclosure - INCOME TAXES - Narrative Tax Losses, Tax Credits and Other Tax Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESNarrativeTaxLossesTaxCreditsandOtherTaxBenefitsDetails</Role>
      <ShortName>INCOME TAXES - Narrative Tax Losses, Tax Credits and Other Tax Benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>162</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R163.htm</HtmlFileName>
      <LongName>9955649 - Disclosure - INCOME TAXES - Tax Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESTaxLossesDetails</Role>
      <ShortName>INCOME TAXES - Tax Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>163</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R164.htm</HtmlFileName>
      <LongName>9955650 - Disclosure - INCOME TAXES - Tax Credits and Other Tax Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/INCOMETAXESTaxCreditsandOtherTaxBenefitsDetails</Role>
      <ShortName>INCOME TAXES - Tax Credits and Other Tax Benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>164</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R165.htm</HtmlFileName>
      <LongName>9955651 - Disclosure - EQUITY - Share Details and Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYShareDetailsandReconciliationDetails</Role>
      <ShortName>EQUITY - Share Details and Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>165</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R166.htm</HtmlFileName>
      <LongName>9955652 - Disclosure - EQUITY - Authorized Shares (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYAuthorizedSharesDetails</Role>
      <ShortName>EQUITY - Authorized Shares (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>166</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R167.htm</HtmlFileName>
      <LongName>9955653 - Disclosure - EQUITY - Share Buyback and Treasury Shares (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYShareBuybackandTreasurySharesDetails</Role>
      <ShortName>EQUITY - Share Buyback and Treasury Shares (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>167</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R168.htm</HtmlFileName>
      <LongName>9955654 - Disclosure - EQUITY - Narrative Equity Instruments and Hybrid Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYNarrativeEquityInstrumentsandHybridInstrumentsDetails</Role>
      <ShortName>EQUITY - Narrative Equity Instruments and Hybrid Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>168</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R169.htm</HtmlFileName>
      <LongName>9955655 - Disclosure - EQUITY - Earnings per Common Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYEarningsperCommonShareDetails</Role>
      <ShortName>EQUITY - Earnings per Common Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>169</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R170.htm</HtmlFileName>
      <LongName>9955656 - Disclosure - EQUITY - Dividends (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYDividendsDetails</Role>
      <ShortName>EQUITY - Dividends (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>170</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R171.htm</HtmlFileName>
      <LongName>9955657 - Disclosure - EQUITY - Non-wholly Owned Subsidiaries that Have Material Non-controlling Interests (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYNonwhollyOwnedSubsidiariesthatHaveMaterialNoncontrollingInterestsDetails</Role>
      <ShortName>EQUITY - Non-wholly Owned Subsidiaries that Have Material Non-controlling Interests (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>171</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R172.htm</HtmlFileName>
      <LongName>9955658 - Disclosure - EQUITY - Transactions with Non-controlling Interests (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/EQUITYTransactionswithNoncontrollingInterestsDetails</Role>
      <ShortName>EQUITY - Transactions with Non-controlling Interests (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>172</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R173.htm</HtmlFileName>
      <LongName>9955659 - Disclosure - RELATED PARTIES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/RELATEDPARTIESNarrativeDetails</Role>
      <ShortName>RELATED PARTIES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>173</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R174.htm</HtmlFileName>
      <LongName>9955660 - Disclosure - RELATED PARTIES - Sales and Trade Receivables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/RELATEDPARTIESSalesandTradeReceivablesDetails</Role>
      <ShortName>RELATED PARTIES - Sales and Trade Receivables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>174</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R175.htm</HtmlFileName>
      <LongName>9955661 - Disclosure - RELATED PARTIES - Purchases and Trade Payables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/RELATEDPARTIESPurchasesandTradePayablesDetails</Role>
      <ShortName>RELATED PARTIES - Purchases and Trade Payables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>175</Position>
    </Report>
    <Report instance="mt-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R176.htm</HtmlFileName>
      <LongName>9955662 - Disclosure - RELATED PARTIES - Other Transactions With Related Parties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corporate.arcelormittal.com/role/RELATEDPARTIESOtherTransactionsWithRelatedPartiesDetails</Role>
      <ShortName>RELATED PARTIES - Other Transactions With Related Parties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>176</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="20-F" isDefinitelyFs="true" isIfrs="true" isUsgaap="true" original="mt-20251231.htm">mt-20251231.htm</File>
    <File>mt-20251231.xsd</File>
    <File>mt-20251231_cal.xml</File>
    <File>mt-20251231_def.xml</File>
    <File>mt-20251231_lab.xml</File>
    <File>mt-20251231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>mt-20251231_g1.gif</File>
    <File>mt-20251231_g10.jpg</File>
    <File>mt-20251231_g11.jpg</File>
    <File>mt-20251231_g12.jpg</File>
    <File>mt-20251231_g13.jpg</File>
    <File>mt-20251231_g14.jpg</File>
    <File>mt-20251231_g15.jpg</File>
    <File>mt-20251231_g16.jpg</File>
    <File>mt-20251231_g17.jpg</File>
    <File>mt-20251231_g18.jpg</File>
    <File>mt-20251231_g19.jpg</File>
    <File>mt-20251231_g2.jpg</File>
    <File>mt-20251231_g20.jpg</File>
    <File>mt-20251231_g21.jpg</File>
    <File>mt-20251231_g22.jpg</File>
    <File>mt-20251231_g23.jpg</File>
    <File>mt-20251231_g24.gif</File>
    <File>mt-20251231_g25.gif</File>
    <File>mt-20251231_g26.gif</File>
    <File>mt-20251231_g27.gif</File>
    <File>mt-20251231_g28.gif</File>
    <File>mt-20251231_g29.gif</File>
    <File>mt-20251231_g3.gif</File>
    <File>mt-20251231_g30.gif</File>
    <File>mt-20251231_g31.gif</File>
    <File>mt-20251231_g32.jpg</File>
    <File>mt-20251231_g33.jpg</File>
    <File>mt-20251231_g34.jpg</File>
    <File>mt-20251231_g35.jpg</File>
    <File>mt-20251231_g36.jpg</File>
    <File>mt-20251231_g4.jpg</File>
    <File>mt-20251231_g5.jpg</File>
    <File>mt-20251231_g6.jpg</File>
    <File>mt-20251231_g7.jpg</File>
    <File>mt-20251231_g8.jpg</File>
    <File>mt-20251231_g9.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="1">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="15">http://xbrl.sec.gov/cyd/2025</BaseTaxonomy>
    <BaseTaxonomy items="41">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="1">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
    <BaseTaxonomy items="5436">https://xbrl.ifrs.org/taxonomy/2025-03-27/ifrs-full</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
