XML 70 R44.htm IDEA: XBRL DOCUMENT
v3.8.0.1

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2017
Environmental Remediation Obligations [Abstract] |
Schedule of Environmental Loss Contingencies and Asset Retirement Obligations [Table Text Block] | The following is a summary of the obligations as of December 31, 2017 and 2016:
| (In Millions)
| December 31,
| 2017 |  | 2016
Environmental | $ | 2.9 |  |  | $ | 2.8 |
Mine closure |  |  |
U.S. Iron Ore 1 | 168.4 |  |  | 187.8 |
Asia Pacific Iron Ore | 28.8 |  |  | 16.2 |
Total mine closure | 197.2 |  |  | 204.0 |
Total environmental and mine closure obligations | 200.1 |  |  | 206.8 |
Less current portion | 3.6 |  |  | 12.9 |
Long-term environmental and mine closure obligations | $ | 196.5 |  |  | $ | 193.9 |
1 U.S. Iron Ore 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 December 31, 2017 and 2016:
| (In Millions)
| December 31,
| 2017 |  | 2016
Asset retirement obligation at beginning of year | $ | 204.0 |  |  | $ | 230.4 |
Accretion expense | 14.9 |  |  | 14.0 |
Remediation payments | (5.6 | ) |  | (2.2 | )
Exchange rate changes | 1.5 |  |  | (0.2 | )
Revision in estimated cash flows | (17.6 | ) |  | (38.0 | )
Asset retirement obligation at end of year | $ | 197.2 |  |  | $ | 204.0 |

X
- Definition Schedule of Environmental Loss Contingencies and Asset Retirement Obligations [Table Text Block] + References No definition available. + Details
Name: | clf_ScheduleofEnvironmentalLossContingenciesandAssetRetirementObligationsTableTextBlock
Namespace Prefix: | clf_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_EnvironmentalRemediationObligationsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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://www.xbrl.org/2003/role/presentationRef -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
Name: | us-gaap_ScheduleOfChangeInAssetRetirementObligationTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration