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DISCONTINUED OPERATIONS (Narrative) (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 USD ($) | Dec. 31, 2018 CAD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Jun. 29, 2018 USD ($) | Jan. 01, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Disposal Group, Including Discontinued Operation, Foreign Currency Translation Gains (Losses) | $ 228,100,000 |  |  |  |  |
Cash Contribution |  | $ 19.0 |  |  |  |
Cost Method Investments |  |  |  |  | $ 0 |
Loans to and accounts receivables from the Canadian Entities | 0 |  | $ 51,600,000 |  |  | $ 51,600,000
Contingent claims | 0 |  | 55,600,000 |  |  | $ 55,600,000
Short-term loan receivable |  |  | 7,700,000 |  |  |
INCOME FROM DISCONTINUED OPERATIONS, net of tax | 88,200,000 |  | 2,500,000 | $ 76,700,000 |  |
Canadian Entities [Member] |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Income tax benefit (expense) | (15,900,000) |  | 0 | 0 |  |
Cost Method Investments |  |  | 0 |  |  |
Loans to and accounts receivables from the Canadian Entities |  |  | 51,600,000 |  |  |
Contingent Liabilities recognized in Consolidated Financials |  |  |  | 37,200,000 |  |
INCOME FROM DISCONTINUED OPERATIONS, net of tax | (26,500,000) |  | (21,300,000) | (17,500,000) |  |
North American Coal [Member] |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Income tax benefit (expense) | 1,000,000 |  | 0 | 0 |  |
INCOME FROM DISCONTINUED OPERATIONS, net of tax | $ (3,600,000) |  | 2,600,000 | $ (2,400,000) |  |
Wabush Scully Mine Sale [Member] |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
INCOME FROM DISCONTINUED OPERATIONS, net of tax |  |  | $ 31,400,000 |  |  |

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