GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES - Goodwill (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
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| Goodwill [Roll Forward] | ||
| Beginning balance | $ 1,768 | $ 1,005 |
| Stelco Acquisition | 16 | 786 |
| Sale of business | (6) | 0 |
| Foreign currency translation | 36 | (23) |
| Ending balance | 1,814 | 1,768 |
| Steelmaking | ||
| Goodwill [Roll Forward] | ||
| Beginning balance | 1,719 | 956 |
| Stelco Acquisition | 16 | 786 |
| Sale of business | (6) | 0 |
| Foreign currency translation | 36 | (23) |
| Ending balance | 1,765 | 1,719 |
| Other Businesses | ||
| Goodwill [Roll Forward] | ||
| Beginning balance | 49 | 49 |
| Stelco Acquisition | 0 | 0 |
| Sale of business | 0 | 0 |
| Foreign currency translation | 0 | 0 |
| Ending balance | $ 49 | $ 49 |
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- Definition Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of foreign currency translation gain (loss) which increases (decreases) asset representing future economic benefit from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of increase (decrease) of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- 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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