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CAPITAL STOCK - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions |  |  |  | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 01, 2021 | Mar. 11, 2021 | Dec. 09, 2020 | Sep. 30, 2021 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Feb. 10, 2022 | Apr. 29, 2021 | Mar. 31, 2021 | Feb. 11, 2021 | Dec. 31, 2020
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Authorized amount of stock repurchase |  |  |  |  |  |  |  | $ 1,000 |  |  |  |
Repurchase of common shares |  |  |  |  | $ 152 | $ 240 | $ 0 |  |  |  |  |
Remaining authorized purchase amount |  |  |  |  | $ 608 |  |  |  |  |  |  |
1.500% 2025 Convertible Senior Notes redemption |  |  |  |  |  | $ (25) | $ (5) |  |  |  |  |
Common shares, issued (in shares) |  |  |  |  | 531,051,530 | 531,051,530 |  |  |  |  | 20,000,000 |
Common shares, sold (in shares) |  |  |  |  |  |  |  |  |  |  | 40,000,000 |
Common stock, shares issued, price per share (in usd per share) |  |  |  |  |  |  |  |  |  |  | $ 16.12 |
Redeemable preferred stock, issued (in shares) |  |  |  |  |  |  |  |  |  |  |  | 583,273
Redeemable preferred stock, outstanding (in shares) |  |  |  |  |  |  |  |  |  |  |  | 583,273
Common shares, authorized (in shares) |  |  |  |  | 1,200,000,000 | 1,200,000,000 |  |  | 1,200,000,000 | 600,000,000 |  |
Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common stock repurchases (in shares) |  |  |  |  | 10,400,000 | 12,500,000 |  |  |  |  |  |
1.500% 2025 Convertible Senior Notes redemption (in shares) |  |  |  |  |  | 24,200,000 |  |  |  |  |  |
Common Shares in Treasury |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common shares |  |  |  |  | $ 152 |  |  |  |  |  |  |
1.500% 2025 Convertible Senior Notes |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Redemption of debt | $ 294 |  |  |  |  |  |  |  |  |  |  |
Repayments of debt | 294 |  |  |  |  |  |  |  |  |  |  |
1.500% 2025 Convertible Senior Notes redemption | $ 499 |  |  |  |  |  |  |  |  |  |  |
9.875% 2025 Senior Secured Notes |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Redemption of debt |  | $ 322 |  |  |  |  |  |  |  |  |  |
ArcelorMittal |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common shares, sold (in shares) |  |  |  |  |  |  |  |  |  |  | 40,000,000 |
Common Stock |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
1.500% 2025 Convertible Senior Notes redemption (in shares) | 24,000,000 |  |  |  |  |  |  |  |  |  |  |
Common Stock | ArcelorMittal USA |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Acquisition (in shares) |  |  | 78,000,000 |  |  |  |  |  |  |  |  |
Series B Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stock redeemed during period (in shares) |  |  |  | 583,273 |  |  |  |  |  |  |  |
Stock redeemed during period |  |  |  | $ 1,300 |  |  |  |  |  |  |  |
Preferred stock authorized (in shares) |  |  |  |  | 4,000,000 |  |  |  |  |  |  |
Preferred stock issued (in shares) |  |  |  |  | 0 |  |  |  |  |  |  |
Preferred stock outstanding (in shares) |  |  |  |  | 0 |  |  |  |  |  |  |
Series A Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock authorized (in shares) |  |  |  |  | 3,000,000 |  |  |  |  |  |  |
Preferred stock issued (in shares) |  |  |  |  | 0 |  |  |  |  |  |  |
Preferred stock outstanding (in shares) |  |  |  |  | 0 |  |  |  |  |  |  |

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- Definition The number of securities classified as temporary equity that have been sold (or granted) to the entity's shareholders. Securities issued include securities outstanding and securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(27)(b)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
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- Definition The number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(27)(b)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
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