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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 - Canadian Entities (Details)

v2.4.1.9
DISCONTINUED OPERATIONS Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis - Canadian Entities (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Canadian Entities [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure $ 112.1clf_LoanstoandAccountsReceivablesfromBloomLakeGroupFairValueDisclosure
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_CanadianEntitiesMember
Losses on Loans to and Accounts Receivables from the Bloom Lake Group (476.0)clf_LossesonLoanstoandAccountsReceivablesfromtheBloomLakeGroup
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_CanadianEntitiesMember
Bloom Lake Group [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure 342.7clf_ContingentLiabilitiesandJointandSeveralLiabilitiesFairValueDisclosure
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_BloomLakeGroupMember
Losses on Contingent Liabilities and Joint and Several Liabilities (342.7)clf_LossesonContingentLiabilitiesandJointandSeveralLiabilities
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_BloomLakeGroupMember
Fair Value, Inputs, Level 1 [Member] | Canadian Entities [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure 0clf_LoanstoandAccountsReceivablesfromBloomLakeGroupFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_CanadianEntitiesMember
Fair Value, Inputs, Level 1 [Member] | Bloom Lake Group [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure 0clf_ContingentLiabilitiesandJointandSeveralLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_BloomLakeGroupMember
Fair Value, Inputs, Level 2 [Member] | Canadian Entities [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure 0clf_LoanstoandAccountsReceivablesfromBloomLakeGroupFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_CanadianEntitiesMember
Fair Value, Inputs, Level 2 [Member] | Bloom Lake Group [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure 0clf_ContingentLiabilitiesandJointandSeveralLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_BloomLakeGroupMember
Fair Value, Inputs, Level 3 [Member] | Canadian Entities [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure 112.1clf_LoanstoandAccountsReceivablesfromBloomLakeGroupFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_CanadianEntitiesMember
Fair Value, Inputs, Level 3 [Member] | Bloom Lake Group [Member] Ìý
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] Ìý
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure $ 342.7clf_ContingentLiabilitiesandJointandSeveralLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= clf_BloomLakeGroupMember