CAPITAL STOCK - Narrative (Details) $ / shares in Units, $ in Millions |
3 Months Ended | 12 Months Ended | ||||||||||
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Mar. 11, 2021
USD ($)
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Dec. 09, 2020
shares
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Apr. 24, 2020
USD ($)
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Mar. 13, 2020
USD ($)
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Sep. 30, 2021
USD ($)
shares
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Jun. 30, 2021
USD ($)
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Dec. 31, 2021
USD ($)
$ / shares
shares
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Dec. 31, 2020
USD ($)
$ / shares
shares
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Dec. 31, 2019
USD ($)
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Apr. 29, 2021
shares
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Mar. 31, 2021
shares
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Feb. 11, 2021
$ / shares
shares
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Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Common shares, issued (in shares) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 506,832,537 | 506,832,537 | Ìý | Ìý | Ìý | 20,000,000 |
Common Stock, Shares, Sold | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 40,000,000 |
Common stock, shares issued, price per share | $ / shares | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 16.12 |
Debt Extinguished | $ | Ìý | Ìý | $ 736 | Ìý | Ìý | Ìý | $ 1,306 | $ 1,513 | $ 724 | Ìý | Ìý | Ìý |
Common shares, par value (in dollars per share) | $ / shares | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 0.125 | $ 0.125 | Ìý | Ìý | Ìý | Ìý |
Redeemable preferred stock, issued (in shares) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0 | 583,273 | Ìý | Ìý | Ìý | Ìý |
Redeemable preferred stock, outstanding (in shares) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0 | 583,273 | Ìý | Ìý | Ìý | Ìý |
Common shares, authorized (in shares) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 1,200,000,000 | 600,000,000 | Ìý | 1,200,000,000 | 600,000,000 | Ìý |
Repurchase of common shares | $ | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 0 | $ 0 | $ 253 | Ìý | Ìý | Ìý |
9.875% 2025 Senior Secured Notes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Debt Extinguished | $ | $ 322 | Ìý | Ìý | Ìý | Ìý | $ 25 | $ 347 | Ìý | Ìý | Ìý | Ìý | Ìý |
ArcelorMittal | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Common Stock, Shares, Sold | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 40,000,000 |
ÐÇ¿Õ´«Ã½ Inc. | 9.875% 2025 Senior Secured Notes | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Stated interest rate | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 9.875% | 9.875% | Ìý | Ìý | Ìý | Ìý |
AK Steel | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Exchange ratio | Ìý | Ìý | Ìý | 0.400 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Common Stock | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Common shares, par value (in dollars per share) | $ / shares | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 0.125 | Ìý | Ìý | Ìý | Ìý | Ìý |
Stock Repurchased During Period, Shares | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 24,000,000 | Ìý | Ìý | Ìý | Ìý |
Common Stock | ArcelorMittal USA | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Acquisition (in shares) | Ìý | 78,186,671 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Common Stock | AK Steel | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Acquisition (in shares) | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 127,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý |
Exchange ratio | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0.400 | Ìý | Ìý | Ìý | Ìý | Ìý |
Fair value of Cliffs common shares issued for outstanding AK Steel common stock | $ | Ìý | Ìý | Ìý | $ 618 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Series B Preferred Stock | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Stock Redeemed or Called During Period, Shares | Ìý | Ìý | Ìý | Ìý | 583,273 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Stock Redeemed or Called During Period, Value | $ | Ìý | Ìý | Ìý | Ìý | $ 1,300 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Preferred Stock, Shares Authorized | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 4,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý |
Preferred Stock, Shares Issued | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0 | Ìý | Ìý | Ìý | Ìý | Ìý |
Preferred Stock, Shares Outstanding | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0 | Ìý | Ìý | Ìý | Ìý | Ìý |
Series B Preferred Stock | ArcelorMittal USA | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Acquisition (in shares) | Ìý | 583,273 | Ìý | Ìý | Ìý | Ìý | 583,273 | Ìý | Ìý | Ìý | Ìý | Ìý |
Series A Preferred Stock | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Class of Stock [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
Preferred Stock, Shares Authorized | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 3,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý |
Preferred Stock, Shares Issued | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0 | Ìý | Ìý | Ìý | Ìý | Ìý |
Preferred Stock, Shares Outstanding | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 0 | Ìý | Ìý | Ìý | Ìý | Ìý |
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- Definition Business Acquisition, Shares Exchange Ratio No definition available.
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- Definition Common Stock, Shares, Sold No definition available.
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- Definition Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Face amount or stated value per share of common stock. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Gross amount of debt extinguished. No definition available.
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- Definition The cash outflow to reacquire common stock during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Per share or per unit amount of equity securities issued. No definition available.
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- 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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- Definition Number of stock bought back by the entity at the exercise price or redemption price. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Equity impact of the value of stock bought back by the entity at the exercise price or redemption price. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- 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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- 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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