XML 105 R91.htm IDEA: XBRL DOCUMENT
v3.5.0.2

RELATED PARTIES (Summary Of Other Ownership Interests) (Details) | Sep. 30, 2016
--- | ---
Hibbing [Member] | Arcelor Mittal [Member] |
Related Party Transaction [Line Items] |
Ownership interest, equity method investment | 62.30%
Hibbing [Member] | U. S. Steel Canada [Member] |
Related Party Transaction [Line Items] |
Ownership interest, equity method investment | 14.70%
Empire [Member] |
Related Party Transaction [Line Items] |
Noncontrolling Interest, Ownership Percentage by Parent | 79.00%
Empire [Member] | Arcelor Mittal [Member] |
Related Party Transaction [Line Items] |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners | 21.00%
Empire [Member] | U. S. Steel Canada [Member] |
Related Party Transaction [Line Items] |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners | 0.00%
Tilden [Member] |
Related Party Transaction [Line Items] |
Noncontrolling Interest, Ownership Percentage by Parent | 85.00%
Tilden [Member] | Arcelor Mittal [Member] |
Related Party Transaction [Line Items] |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners | 0.00%
Tilden [Member] | U. S. Steel Canada [Member] |
Related Party Transaction [Line Items] |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners | 15.00%
Other Noncurrent Assets [Member] | Hibbing [Member] |
Related Party Transaction [Line Items] |
Ownership interest, equity method investment | 23.00%

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=clf_HibbingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=clf_ArcelorMittalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=clf_USSteelCanadaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | clf_NameofOperationAxis=clf_EmpireMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | clf_NameofOperationAxis=clf_TildenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |