Name:	ifrs-full_DisclosureOfJointVenturesLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of investments in equity instruments that the entity has designated at fair value through other comprehensive income. [Refer: At fair value [member]; Other comprehensive income]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2022-03-24
-Paragraph 11A
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2022-en-r&anchor=para_11A_c&doctype=Standard
-URIDate 2022-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2022-03-24
-Paragraph 8
-Subparagraph h
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2022-en-r&anchor=para_8_h&doctype=Standard
-URIDate 2022-03-24

Name:	ifrs-full_FairValueOfInvestmentsInEquityInstrumentsDesignatedAsMeasuredAtFairValueThroughOtherComprehensiveIncome
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of investments in joint ventures accounted for using the equity method. [Refer: Joint ventures [member]; Investments accounted for using equity method]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2022-03-24
-Paragraph 55
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_55&doctype=Standard
-URIDate 2022-03-24

Name:	ifrs-full_InvestmentsInJointVenturesAccountedForUsingEquityMethod
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The proportion of ownership interest in a joint operation attributable to the entity. [Refer: Joint operations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2022-03-24
-Paragraph 21
-Subparagraph a
-Clause iv
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2022-en-r&anchor=para_21_a_iv&doctype=Standard
-URIDate 2022-03-24

Name:	ifrs-full_ProportionOfOwnershipInterestInJointOperation
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

A component of equity representing the accumulated revaluation surplus on the revaluation of assets recognised in other comprehensive income. [Refer: Other comprehensive income]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 38
-IssueDate 2022-03-24
-Paragraph 85
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=38&code=ifrs-tx-2022-en-r&anchor=para_85&doctype=Standard
-URIDate 2022-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2022-03-24
-Paragraph 39
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=16&code=ifrs-tx-2022-en-r&anchor=para_39&doctype=Standard
-URIDate 2022-03-24

Name:	ifrs-full_RevaluationSurplus
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Deferred Consideration

No definition available.

Name:	mt_DeferredConsideration
Namespace Prefix:	mt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Number Of Investments Completed

No definition available.

Name:	mt_NumberOfInvestmentsCompleted
Namespace Prefix:	mt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Number Of Mega Watts Wind Power Project

No definition available.

Name:	mt_NumberOfMegaWattsWindPowerProject
Namespace Prefix:	mt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Number Of Shares Sold, Investments In Equity Instruments

No definition available.

Name:	mt_NumberOfSharesSoldInvestmentsInEquityInstruments
Namespace Prefix:	mt_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Number Of Years Power Purchasing Agreement

No definition available.

Name:	mt_NumberOfYearsPowerPurchasingAgreement
Namespace Prefix:	mt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Proceeds From Sales Of Investments At Fair Value Through Other Comprehensive Income

No definition available.

Name:	mt_ProceedsFromSalesOfInvestmentsAtFairValueThroughOtherComprehensiveIncome
Namespace Prefix:	mt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Proportion Of Ownership Interest In Investment

No definition available.