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ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Tables) | 12 Months Ended
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Dec. 31, 2018
Environmental Remediation Obligations [Abstract] |
Schedule of Environmental Loss Contingencies and Asset Retirement Obligations [Table Text Block] | The following is a summary of our environmental and mine closure obligations:
| (In Millions)
| December 31,
| 2018 |  | 2017
Environmental | $ | 2.5 |  |  | $ | 2.9 |
Mine closure 1 | 172.4 |  |  | 168.4 |
Total environmental and mine closure obligations | 174.9 |  |  | 171.3 |
Less current portion | 2.9 |  |  | 3.6 |
Long-term environmental and mine closure obligations | $ | 172.0 |  |  | $ | 167.7 |
1 Includes our active operating mines, our indefinitely idled Empire mine and a closed mine formerly operating as LTVSMC.
Asset Retirement Obligations | The following represents a roll forward of our asset retirement obligation liability for the years ended:
| (In Millions)
| December 31,
| 2018 |  | 2017
Asset retirement obligation at beginning of year | $ | 168.4 |  |  | $ | 187.8 |
Accretion expense | 9.5 |  |  | 13.9 |
Remediation payments | (1.0 | ) |  | (5.6 | )
Revision in estimated cash flows | (4.5 | ) |  | (27.7 | )
Asset retirement obligation at end of year | $ | 172.4 |  |  | $ | 168.4 |

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- Definition Tabular disclosure of the changes in carrying amount of a liability for asset retirement obligations, for changes such as new obligations, changes in estimates of existing obligations, spending on existing obligations, property dispositions, and foreign currency translation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859 + Details
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