ASSET RETIREMENT OBLIGATIONS (Summary Of Asset Retirement Obligations) (Details) - USD ($) $ in Millions |
Mar. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
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| Loss Contingencies [Line Items] | Ìý | Ìý | Ìý | ||||
| Asset Retirement Obligation | $ 181.4 | [1] | $ 165.3 | [1] | $ 172.4 | ||
| Asset Retirement Obligation, Current | 2.2 | 2.1 | Ìý | ||||
| Asset Retirement Obligations, Noncurrent | 179.2 | 163.2 | Ìý | ||||
| Operating Segments [Member] | Mining and Pelletizing [Member] | Ìý | Ìý | Ìý | ||||
| Loss Contingencies [Line Items] | Ìý | Ìý | Ìý | ||||
| Asset Retirement Obligation | $ 32.5 | $ 22.0 | Ìý | ||||
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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. 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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