ÈÕº«Èý¼¶Æ¬

Quarterly report pursuant to Section 13 or 15(d)

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued ÈÕº«Èý¼¶Æ¬, Assets and Liabilities - Canadian Entities (Details)

v2.4.1.9
DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued ÈÕº«Èý¼¶Æ¬, Assets and Liabilities - Canadian Entities (Details) (Canadian Entities [Member], USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Canadian Entities [Member]
Ìý Ìý
Schedule of Disposal Groups, Including Discontinued ÈÕº«Èý¼¶Æ¬, Assets and Liabilities [Line Items] Ìý Ìý
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents Ìý $ 19.7us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net 3.0us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
37.9us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Inventory Ìý 16.3us-gaap_DisposalGroupIncludingDiscontinuedOperationInventory1
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal group, including Discontinued ÈÕº«Èý¼¶Æ¬, Prepaid Supplies Ìý 48.5clf_DisposalgroupincludingDiscontinuedÈÕº«Èý¼¶Æ¬PrepaidSupplies
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal group, including Discontinued ÈÕº«Èý¼¶Æ¬, Income taxes receivable 1.8clf_DisposalgroupincludingDiscontinuedÈÕº«Èý¼¶Æ¬Incometaxesreceivable
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
20.1clf_DisposalgroupincludingDiscontinuedÈÕº«Èý¼¶Æ¬Incometaxesreceivable
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Other Assets, Current Ìý 44.3us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment Ìý 249.8us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent 3.8us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
19.9us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Assets 8.6us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
456.5us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Accounts Payable 0.5us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayable
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
83.6us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayable
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Accrued Liabilities 51.1us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilities
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
200.0us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilities
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Other Liabilities, Current Ìý 35.7us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal group, Including Discontinued Operation, Pension and Other Postretirement Obligations Ìý 79.8clf_DisposalgroupIncludingDiscontinuedOperationPensionandOtherPostretirementObligations
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group Including Discontinued ÈÕº«Èý¼¶Æ¬ Environmental Loss Contingency And Mine Reclamation And Closing Liability CurrentAnd Noncurrent Ìý 56.5clf_DisposalGroupIncludingDiscontinuedÈÕº«Èý¼¶Æ¬EnvironmentalLossContingencyAndMineReclamationAndClosingLiabilityCurrentAndNoncurrent
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent 140.9us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
173.9us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
Disposal Group, Including Discontinued Operation, Liabilities $ 192.5us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember
$ 629.5us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedÈÕº«Èý¼¶Æ¬Axis
= clf_CanadianEntitiesMember