Statements of Consolidated Changes in Equity - USD ($) $ in Millions |
Total |
AK Steel [Member] |
ArcelorMittal USA [Member] |
Common Stock [Member] |
Common Stock [Member]
AK Steel [Member]
|
Common Stock [Member]
ArcelorMittal USA [Member]
|
Capital in Excess of Par Value of Shares [Member] |
Capital in Excess of Par Value of Shares [Member]
AK Steel [Member]
|
Capital in Excess of Par Value of Shares [Member]
ArcelorMittal USA [Member]
|
Retained Earnings [Member] |
Common Shares in Treasury [Member] |
Accumulated Other Comprehensive Income (Loss) [Member] |
Noncontrolling Interest [Member] |
Noncontrolling Interest [Member]
AK Steel [Member]
|
Noncontrolling Interest [Member]
ArcelorMittal USA [Member]
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Balance, beginning of period (in shares) at Dec. 31, 2017 | Ìý | Ìý | Ìý | 297,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Balance, beginning of period at Dec. 31, 2017 | $ (445) | Ìý | Ìý | $ 37 | Ìý | Ìý | $ 3,934 | Ìý | Ìý | $ (4,207) | $ (170) | $ (39) | $ 0 | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Adoption of accounting standard | Accounting Standards Update 2014-09 | 34 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 34 | Ìý | Ìý | Ìý | Ìý | Ìý |
| Comprehensive income | 883 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 1,128 | Ìý | (245) | 0 | Ìý | Ìý |
| Stock and other incentive plans (in shares) | Ìý | Ìý | Ìý | 1,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock and other incentive plans, APIC | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (17) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock and other incentive plans | 14 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 31 | Ìý | Ìý | Ìý | Ìý |
| Common stock repurchases (in shares) | Ìý | Ìý | Ìý | (5,000,000) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Common stock repurchased (value) | $ (47) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (47) | Ìý | Ìý | Ìý | Ìý |
| Common Stock, Dividends, Per Share, Declared | $ 0.05 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Common stock dividends | $ (15) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (15) | Ìý | Ìý | Ìý | Ìý | Ìý |
| Balance, end of period (in shares) at Dec. 31, 2018 | Ìý | Ìý | Ìý | 293,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Balance, end of period at Dec. 31, 2018 | 424 | Ìý | Ìý | $ 37 | Ìý | Ìý | 3,917 | Ìý | Ìý | (3,060) | (186) | (284) | 0 | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Comprehensive income | 258 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 293 | Ìý | (35) | 0 | Ìý | Ìý |
| Stock and other incentive plans (in shares) | Ìý | Ìý | Ìý | 2,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock and other incentive plans, APIC | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (44) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock and other incentive plans | 4 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 48 | Ìý | Ìý | Ìý | Ìý |
| Common stock repurchases (in shares) | Ìý | Ìý | Ìý | (24,000,000) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Common stock repurchased (value) | $ (253) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (253) | Ìý | Ìý | Ìý | Ìý |
| Common Stock, Dividends, Per Share, Declared | $ 0.27 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Common stock dividends | $ (75) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (75) | Ìý | Ìý | Ìý | Ìý | Ìý |
| Balance, end of period (in shares) at Dec. 31, 2019 | 270,084,005 | Ìý | Ìý | 271,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Balance, end of period at Dec. 31, 2019 | $ 358 | Ìý | Ìý | $ 37 | Ìý | Ìý | 3,873 | Ìý | Ìý | (2,842) | (391) | (319) | 0 | Ìý | Ìý |
| Increase (Decrease) in Stockholders' Equity [Roll Forward] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Comprehensive income | 105 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (122) | Ìý | 186 | 41 | Ìý | Ìý |
| Stock and other incentive plans (in shares) | Ìý | Ìý | Ìý | 2,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock and other incentive plans, APIC | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (24) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock and other incentive plans | $ 13 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 37 | Ìý | Ìý | Ìý | Ìý |
| Stock Issued During Period, Shares, Acquisitions | Ìý | Ìý | Ìý | Ìý | 127,000,000 | 78,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Stock Issued During Period, Value, Acquisitions | Ìý | $ 948 | $ 1,003 | Ìý | $ 16 | $ 10 | Ìý | $ 602 | $ 980 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Noncontrolling Interest, Increase from Business Combination | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 330 | $ 13 |
| Common Stock, Dividends, Per Share, Declared | $ 0.06 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Common stock dividends | $ (25) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (25) | Ìý | Ìý | Ìý | Ìý | Ìý |
| Distributions of partnership equity | $ (61) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | (61) | Ìý | Ìý |
| Balance, end of period (in shares) at Dec. 31, 2020 | 477,517,372 | Ìý | Ìý | 478,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Balance, end of period at Dec. 31, 2020 | $ 2,341 | Ìý | Ìý | $ 63 | Ìý | Ìý | $ 5,431 | Ìý | Ìý | $ (2,989) | $ (354) | $ (133) | $ 323 | Ìý | Ìý |
| X | ||||||||||
- Definition Amount of increase to additional paid-in capital (APIC) for recognition of cost for award under share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
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| X | ||||||||||
- Definition Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Amount of increase in noncontrolling interest from a business combination. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number of shares of stock issued during the period pursuant to acquisitions. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Value of stock issued pursuant to acquisitions during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Value, after forfeiture, of shares issued under share-based payment arrangement. Excludes employee stock ownership plan (ESOP). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition The increase (decrease) in stockholders' equity during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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