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Quarterly report pursuant to Section 13 or 15(d)

DISCONTINUED OPERATIONS Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis - North American Coal (Details)

v2.4.1.9
DISCONTINUED OPERATIONS Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis - North American Coal (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring $ 397.2us-gaap_AssetsFairValueDisclosureNonrecurring $ 79.4us-gaap_AssetsFairValueDisclosureNonrecurring
Impairment Charges 269.5clf_ImpairmentCharges 644.7clf_ImpairmentCharges
North American Coal [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 20.4us-gaap_PropertyPlantAndEquipmentFairValueDisclosure
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Tangible Asset Impairment Charges (73.4)us-gaap_TangibleAssetImpairmentCharges
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Assets, Fair Value Disclosure, Nonrecurring 20.4us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Impairment Charges (73.4)clf_ImpairmentCharges
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Fair Value, Inputs, Level 1 [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring 0us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
0us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Fair Value, Inputs, Level 1 [Member] | North American Coal [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0us-gaap_PropertyPlantAndEquipmentFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Assets, Fair Value Disclosure, Nonrecurring 0us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Fair Value, Inputs, Level 2 [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring 397.2us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
0us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Fair Value, Inputs, Level 2 [Member] | North American Coal [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0us-gaap_PropertyPlantAndEquipmentFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Assets, Fair Value Disclosure, Nonrecurring 0us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Fair Value, Inputs, Level 3 [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring 0us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
79.4us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Fair Value, Inputs, Level 3 [Member] | North American Coal [Member] Ìý Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 20.4us-gaap_PropertyPlantAndEquipmentFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý
Assets, Fair Value Disclosure, Nonrecurring $ 20.4us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_NorthAmericanCoalMember
Ìý