Quarterly report pursuant to Section 13 or 15(d)

DEBT AND CREDIT FACILITIES (Narrative) (Details)

v2.4.1.9
DEBT AND CREDIT FACILITIES (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 30, 2015
Dec. 31, 2014
Line of Credit Facility [Line Items]      
Letters of credit outstanding $ 136.2us-gaap_LettersOfCreditOutstandingAmount   $ 149.5us-gaap_LettersOfCreditOutstandingAmount
Five hundred forty million Eight point two five Twenty twenty First Lien Notes [Member]      
Line of Credit Facility [Line Items]      
Stated interest rate 8.25%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Repurchase Price of $540M 8.25% Notes if Triggering Event Occurs 1.01clf_RepurchasePriceof540M8.25NotesifTriggeringEventOccurs
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Initial Redemption Price 1.0825clf_InitialRedemptionPrice
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Redemption Price after 2018 1clf_RedemptionPriceafter2018
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Redemption Price from time to time and Prior to March 31, 2018 1clf_RedemptionPricefromtimetotimeandPriortoMarch312018
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Amount in aggregate that can be redeemed on or prior to March 31, 2018 0.35clf_AmountinaggregatethatcanberedeemedonorpriortoMarch312018
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Redemption Price of 35 percent or less of Outstanding 1.0825clf_RedemptionPriceof35percentorlessofOutstanding
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Amount to Remain Outstanding Prior to March 31, 2018 0.65clf_AmounttoRemainOutstandingPriortoMarch312018
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
In the Event of Default Amount that will Accelerate 0.25clf_IntheEventofDefaultAmountthatwillAccelerate
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Debt Instrument, Par Value 540.0clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredfortymillionEightpointtwofiveTwentytwentyFirstLienNotesMember
   
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]      
Line of Credit Facility [Line Items]      
Stated interest rate 7.75%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Initial Redemption Price 1.03875clf_InitialRedemptionPrice
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Redemption Price beginning March 31, 2019 1clf_RedemptionPricebeginningMarch312019
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Redemption Price from time to time and Prior to March 31, 2017 1clf_RedemptionPricefromtimetotimeandPriortoMarch312017
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Amount in aggregate that can be redeemed on or prior to March 31, 2017 0.35clf_AmountinaggregatethatcanberedeemedonorpriortoMarch312017
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Redemption Price of 35 percent or less of Outstanding 1.0775clf_RedemptionPriceof35percentorlessofOutstanding
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Amount to Remain Outstanding Prior to March 31, 2018 0.65clf_AmounttoRemainOutstandingPriortoMarch312018
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Debt Instrument, Par Value 544.2clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FivehundredFortyfourMillionSevenPointSevenFiveTwentyTwentySecondLienNotesMember
   
Revolving Credit Facility [Member]      
Line of Credit Facility [Line Items]      
Revolving credit facility, borrowing capacity 441.1us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Credit facility, amount outstanding 0us-gaap_LineOfCredit
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
[1]   0us-gaap_LineOfCredit
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
[2]
Debt Instrument, Par Value 550.0clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
900.0clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
1,125.0clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
U.S. Tranche 450.0clf_U.S.Tranche
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Sublimit for Issuers of Letters of Credit for U.S. Tranche 250.0clf_SublimitforIssuersofLettersofCreditforU.S.Tranche
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Sublimit for U.S. Swingline Loans 100.0clf_SublimitforU.S.SwinglineLoans
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Australian Tranche 100.0clf_AustralianTranche
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Sublimit for Issuance of Letters of Credit for Australian Tranche 50.0clf_SublimitforIssuanceofLettersofCreditforAustralianTranche
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Sublimit for Australian Swingline Loans 20.0clf_SublimitforAustralianSwinglineLoans
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Credit facility remaining capacity 299.4us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
  975.5us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
LIBOR Rate Based on a One-month interest period plus 1 percent 0.01clf_LIBORRateBasedonaOnemonthinterestperiodplus1percent
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Fixed Charge Coverage Ratio 1.0clf_FixedChargeCoverageRatio
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Letters of credit outstanding 136.2us-gaap_LettersOfCreditOutstandingAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
  149.5us-gaap_LettersOfCreditOutstandingAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
Foreign Exchange Hedge Obligations $ 5.5clf_ForeignExchangeHedgeObligations
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
   
Revolving Credit Facility [Member] | Minimum [Member]      
Line of Credit Facility [Line Items]      
Base Rate 0.005clf_BaseRate
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
   
Revolving Credit Facility [Member] | Maximum [Member]      
Line of Credit Facility [Line Items]      
Base Rate 0.01clf_BaseRate
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
   
[1] As of March 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million as a result of borrowing base limitations. As of March 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby further reducing available borrowing capacity on our ABL Facility to $299.4 million.
[2] As of December 31, 2014, we had no revolving loans drawn under the revolving credit agreement of which had $1.125 billion availability. As of December 31, 2014, the principal amount of letter of credit obligations totaled $149.5 million, thereby further reducing available borrowing capacity on the revolving credit agreement to $975.5 million.