GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES - Goodwill (Details) - USD ($) $ in Millions |
Sep. 30, 2020 |
Dec. 31, 2019 |
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| Goodwill [Line Items] | Ìý | Ìý |
| Goodwill | $ 144.0 | $ 2.1 |
| Steel and Manufacturing [Member] | Ìý | Ìý |
| Goodwill [Line Items] | Ìý | Ìý |
| Goodwill | 141.9 | Ìý |
| Mining and Pelletizing [Member] | Ìý | Ìý |
| Goodwill [Line Items] | Ìý | Ìý |
| Goodwill | $ 2.1 | $ 2.1 |
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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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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