Annual report pursuant to Section 13 and 15(d)

DEBT AND CREDIT FACILITIES (Narrative) (Details)

v2.4.1.9
DEBT AND CREDIT FACILITIES (Narrative) (Details)
 0 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 0 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Aug. 11, 2011
Term Loan [Member]
USD ($)
May 27, 2010
Amapa's Debt [Member]
USD ($)
Dec. 31, 2014
Senior Notes - $400 Million [Member]
USD ($)
Dec. 31, 2013
Senior Notes - $400 Million [Member]
USD ($)
Dec. 31, 2014
Senior Notes - $400 Million [Member]
Maximum [Member]
Dec. 31, 2014
Senior Notes - $400 Million [Member]
Minimum [Member]
Dec. 31, 2014
Five Hundred Million Four Point Eight Zero Percent Senior Note [Member]
USD ($)
Dec. 31, 2013
Five Hundred Million Four Point Eight Zero Percent Senior Note [Member]
USD ($)
Dec. 31, 2014
Five Hundred Million Six Point Two Five Percent Two Thousand And Forty [Member]
USD ($)
Dec. 31, 2014
Senior Notes10 Year Tranche [Member]
USD ($)
Dec. 31, 2014
Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
USD ($)
Dec. 31, 2013
Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
USD ($)
Sep. 22, 2010
Revolving Credit Facility [Member]
USD ($)
Dec. 31, 2014
Revolving Credit Facility [Member]
USD ($)
Dec. 31, 2013
Revolving Credit Facility [Member]
USD ($)
Sep. 30, 2014
Revolving Credit Facility [Member]
USD ($)
Dec. 31, 2012
$270 Million Senior Notes [Member]
USD ($)
Dec. 31, 2012
Series Two Thousand And Eight Tranche B [Member]
USD ($)
Dec. 31, 2014
Senior Notes Five Hundred Million [Member]
Dec. 31, 2014
Senior Notes Five Hundred Million [Member]
Maximum [Member]
Dec. 31, 2014
Senior Notes Five Hundred Million [Member]
Minimum [Member]
Dec. 31, 2014
Five Hundred Million Three Point Nine Five Two Thousand Eighteen Senior Note [Member]
USD ($)
Dec. 31, 2013
Five Hundred Million Three Point Nine Five Two Thousand Eighteen Senior Note [Member]
USD ($)
Dec. 31, 2014
Equipment Loans [Member]
USD ($)
Dec. 31, 2014
Line of Credit [Member]
USD ($)
Dec. 31, 2014
Line of Credit [Member]
AUD
Dec. 31, 2013
Line of Credit [Member]
USD ($)
Dec. 31, 2013
Line of Credit [Member]
AUD
Dec. 31, 2014
Senior Notes30 Year Tranche [Member]
USD ($)
Dec. 31, 2014
Senior Notes One Billion Two Thousand Eleven Offering [Member]
USD ($)
Dec. 31, 2014
Senior Notes One Billion Two Thousand Eleven Offering [Member]
Maximum [Member]
Dec. 31, 2014
Senior Notes One Billion Two Thousand Eleven Offering [Member]
Minimum [Member]
Dec. 31, 2014
Senior Notes One Billion Two Thousand Ten Offering [Member]
USD ($)
Dec. 31, 2014
Senior Notes One Billion Two Thousand Ten Offering [Member]
Maximum [Member]
Dec. 31, 2014
Senior Notes One Billion Two Thousand Ten Offering [Member]
Minimum [Member]
Line of Credit Facility [Line Items]                                                                          
liquidity test                               $ 400,000,000clf_Liquiditytest
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		                                         
Stock Repurchase Program, Authorized Amount 200,000,000us-gaap_StockRepurchaseProgramAuthorizedAmount1                                                                        
Debt Instrument, Repurchased Face Amount         5,000,000us-gaap_DebtInstrumentRepurchasedFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		      10,000,000us-gaap_DebtInstrumentRepurchasedFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		      10,000,000us-gaap_DebtInstrumentRepurchasedFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_SevenHundredMillionFourPointEightSevenFiveTwoThousandTwentyoneSeniorNoteMember 		                    20,000,000us-gaap_DebtInstrumentRepurchasedFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		                         
Long-term Line of Credit, Noncurrent     200,000,000us-gaap_LongTermLineOfCredit
/ us-gaap_DebtInstrumentAxis
= clf_TermLoanMember 		                                                                   
Repayments of Debt       100,800,000us-gaap_RepaymentsOfDebt
/ us-gaap_DebtInstrumentAxis
= clf_AmapasDebtMember 		                    350,000,000us-gaap_RepaymentsOfDebt
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		      270,000,000us-gaap_RepaymentsOfDebt
/ us-gaap_DebtInstrumentAxis
= clf_SeriesTwoThousandAndEightTrancheMember 		55,000,000us-gaap_RepaymentsOfDebt
/ us-gaap_DebtInstrumentAxis
= clf_SeriesTwoThousandAndEightTrancheBMember 		                                 
Revolving credit facility, borrowing capacity                                                     2,500,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		3,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		26,800,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		30,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		             
Debt Instrument, Face Amount         400,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		400,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		    500,000,000.0us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		500,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		500,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionSixPointTwoFivePercentTwoThousandAndFortyMember 		  700,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_SevenHundredMillionFourPointEightSevenFiveTwoThousandTwentyoneSeniorNoteMember 		700,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_SevenHundredMillionFourPointEightSevenFiveTwoThousandTwentyoneSeniorNoteMember 		                  500,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		500,000,000.0us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		          300,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_ThreeHundredMillionSixPointTwoFivePercentTwoThousandAndFortyMember 		1,000,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesOneBillionTwoThousandElevenOfferingMember 		    1,000,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesOneBillionTwoThousandTenOfferingMember 		   
Financial covenant, interest coverage ratio                               3.5clf_CoverageRatioOfEarningsBeforeInterestTaxDepreciationAndAmortizationToTotalInterestExpense
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		2.5clf_CoverageRatioOfEarningsBeforeInterestTaxDepreciationAndAmortizationToTotalInterestExpense
/ 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 		[1]                   1,200,000us-gaap_LineOfCredit
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		1,500,000us-gaap_LineOfCredit
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		20,500,000us-gaap_LineOfCredit
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		23,000,000us-gaap_LineOfCredit
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		             
Credit facility remaining capacity                               1,000,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		1,700,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		                  1,300,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		1,500,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		6,300,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		7,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= us-gaap_LineOfCreditMember 		             
Letters of credit outstanding   48,000,000us-gaap_LettersOfCreditOutstandingAmount                                                                      
Time Period During Which Senior Notes May Be Redeemed at Company's Option, Number of Days From When Prior Notice Sent to Holders             60 days 30 days                           60 days 30 days                   60 days 30 days   60 days 30 days
Note Redemption Price, Percent of Principal Amount to be Redeemed         100.00%clf_NoteRedemptionPricePercentOfPrincipalAmountToBeRedeemed
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		                              100.00%clf_NoteRedemptionPricePercentOfPrincipalAmountToBeRedeemed
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesFiveHundredMillionMember 		                    100.00%clf_NoteRedemptionPricePercentOfPrincipalAmountToBeRedeemed
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesOneBillionTwoThousandElevenOfferingMember 		    100.00%clf_NoteRedemptionPricePercentOfPrincipalAmountToBeRedeemed
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesOneBillionTwoThousandTenOfferingMember 		   
Redemption Price, Percent Of Principal In The Event Of Change Of Control         101.00%clf_RedemptionPricePercentOfPrincipalInEventOfChangeOfControl
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		                              101.00%clf_RedemptionPricePercentOfPrincipalInEventOfChangeOfControl
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesFiveHundredMillionMember 		                    101.00%clf_RedemptionPricePercentOfPrincipalInEventOfChangeOfControl
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesOneBillionTwoThousandElevenOfferingMember 		         
Debt Instrument, Par Value 4,144,800,000clf_DebtInstrumentParValue 4,814,800,000clf_DebtInstrumentParValue     395,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		400,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		    490,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		500,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		    690,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_SevenHundredMillionFourPointEightSevenFiveTwoThousandTwentyoneSeniorNoteMember 		700,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_SevenHundredMillionFourPointEightSevenFiveTwoThousandTwentyoneSeniorNoteMember 		  1,125,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		1,750,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		1,250,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		          480,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		500,000,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		164,800,000clf_DebtInstrumentParValue
/ us-gaap_DebtInstrumentAxis
= clf_EquipmentLoansMember 		                     
Percentage of Stock to Pledge                               65.00%clf_PercentageofStocktoPledge
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		                                         
Total Funded Debt to Total Capitalization                               0.45clf_TotalFundedDebttoTotalCapitalization
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		                                         
Debt to Earnings                                   3.5clf_DebttoEarnings
/ us-gaap_DebtInstrumentAxis
= us-gaap_RevolvingCreditFacilityMember 		                                     
Limit on Increase in Interest Rate Above Initial Interest Rate, Based on Rating Events                                         2.00%clf_LimitOnIncreaseInInterestRateAboveInitialInterestRateBasedOnRatingEvents
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotesFiveHundredMillionMember 		                               
Debt Instrument, Redemption Period, Time Period Prior to Maturity Date                       3 months                                                  
Note Redemption Price if Redemption Period is During Specified Time Period, Percent of Principal Amount to be Redeemed                       100.00%clf_NoteRedemptionPriceIfRedemptionPeriodIsDuringSpecifiedTimePeriodPercentOfPrincipalAmountToBeRedeemed
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotes10YearTrancheMember 		                                                 
Senior Notes, Noncurrent                 $ 500,000,000us-gaap_SeniorLongTermNotes
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		    $ 700,000,000us-gaap_SeniorLongTermNotes
/ us-gaap_DebtInstrumentAxis
= clf_SeniorNotes10YearTrancheMember 		                                                 
Debt Instrument, Interest Rate, Stated Percentage         5.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		5.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FourHundredMillionFivePointNineZeroTwoThousandAndTwentySeniorNoteMember 		    4.80%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		4.80%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionFourPointEightZeroPercentSeniorNoteMember 		    4.875%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_SevenHundredMillionFourPointEightSevenFiveTwoThousandTwentyoneSeniorNoteMember 		                    3.95%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		                         
Interest Rate Due to Rating Downgrades                                               5.70%clf_InterestRateDuetoRatingDowngrades
/ us-gaap_DebtInstrumentAxis
= clf_FiveHundredMillionThreePointNineFiveTwoThousandEighteenSeniorNoteMember 		                         
[1] As of December 31, 2014 and 2013, no revolving loans were drawn under the credit facility. We had total availability of $1.125 billion and $1.75 billion on our credit facility as of December 31, 2014 and 2013, respectively. Additionally, as of December 31, 2014 and December 31, 2013, the principal amount of letter of credit obligations totaled $149.5 million and $8.4 million, respectively, thereby reducing available borrowing capacity to $1.0 billion and $1.7 billion for each period, respectively.