根据第13和15(d)条提交的年度报告

退休金及其他退休后福利(福利义务、计划资产的公允价值及资金净额)(详情)

v2.4.1.9
养老金和其他退休后福利(福利义务、计划资产的公允价值和资金净额)(详细信息)(美元)
除非另有说明,单位为百万
12个月结束
2014年12月31日
2013年12月31日
2012年12月31日
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年初 188.6美元us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 200.5美元us-gaap_DefinedBenefitPlanFairValueOfPlanAssets  
雇主贡献 7.3us-gaap_DefinedBenefitPlanContributionsByEmployer 25.5us-gaap_DefinedBenefitPlanContributionsByEmployer  
计划资产的公允价值-年末 205.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 188.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets  
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 205.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 188.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets  
财务状况表确认的金额:      
非流动负债 (395.2)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent (294.0)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent  
累计其他综合收益确认的金额:      
退休及界定薪酬计划的披露[表格文字组]
下表汇总了与退休计划有关的年度确认费用 2014 2013 2012
 
(百万)
 
2014
 
2013
 
2012
固定收益养老金计划
美元
31.3

 
美元
52.1

 
美元
55.2

固定缴款养老金计划
6.3

 
6.8

 
6.7

其他退休后福利
(0.7
 
17.4

 
28.1

总计
美元
36.9

 
美元
76.3

 
美元
90.0

   
退休金福利〔成员〕      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年初 (1118 0)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(1244。3)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
服务成本(不含费用) 30.8us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
38.9us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
32.0us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
利息成本 49.7us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
45.9us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
48.4us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
计划的修正案 0us-gaap_DefinedBenefitPlanPlanAmendments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
0.8us-gaap_DefinedBenefitPlanPlanAmendments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
保险精算的损失 (14.1)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(29.9)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(30.4)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
设定受益计划,精算(收益)损失变动 141.6clf_DefinedBenefitPlanChangeinActuarialgainloss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(121.8)clf_DefinedBenefitPlanChangeinActuarialgainloss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
福利支付 (87.0)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(72.9)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
参与者的贡献 0us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
联邦政府对已支付福利的补贴 0us-gaap_DefinedBenefitPlanGrossPrescriptionDrugSubsidyReceiptsReceived
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanGrossPrescriptionDrugSubsidyReceiptsReceived
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
汇率增益 (18.2)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(17.2)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
福利义务-年底 (1227)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(1118 0)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(1244。3)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年初 915.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
838.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
计划资产的实际收益 78.7us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
109.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
92.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
参与者的贡献 0clf_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
0clf_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
雇主贡献 60.5us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
53.7us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
福利支付 (87.0)clf_DefinedBenefitPlanPlanAssetsBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(72.9)clf_DefinedBenefitPlanPlanAssetsBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
汇率增益 (17.9)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(13.7)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
计划资产的公允价值-年末 949.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
915.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
838.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 949.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
915.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
838.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
固定收益计划,收益义务 (1227)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(1118 0)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(1244。3)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
计划资金不足 (277.8)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(202.7)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
12月31日确认的金额 (277.8)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(202.7)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
财务状况表确认的金额:      
流动负债 (2.4)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(5.2)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
非流动负债 (275.4)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(197.5)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
确认净额 (277.8)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(202.7)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
累计其他综合收益确认的金额:      
前期服务成本 10.6us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
14.9us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
净精算损失 341.5us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
230.6us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
确认净额 352.1us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
245.5us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
预计2013年其他累计综合收益摊销为定期福利净成本的金额:      
净精算损失 22.3us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
前期服务成本 2.4us-gaap_DefinedBenefitPlanFutureAmortizationOfPriorServiceCostCredit
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
确认净额 24.7us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
固定收益计划,因缩减而确认的净收益(损失) (10.9)us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
固定收益计划,特殊终止福利 3.4us-gaap_DefinedBenefitPlanSpecialTerminationBenefits
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanSpecialTerminationBenefits
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
其他福利[成员]      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年初 (356.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(459.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
服务成本(不含费用) 6.7us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
12.3us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
14.7us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
利息成本 16.2us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
17.3us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
20.6us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
计划的修正案 (0.9)us-gaap_DefinedBenefitPlanPlanAmendments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanPlanAmendments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
保险精算的损失 (5.0)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(11.5)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(11.6)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
设定受益计划,精算(收益)损失变动 51.9clf_DefinedBenefitPlanChangeinActuarialgainloss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(103.3)clf_DefinedBenefitPlanChangeinActuarialgainloss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
福利支付 (27.4)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(28.0)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
参与者的贡献 4.8us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
5.6us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
联邦政府对已支付福利的补贴 0.9us-gaap_DefinedBenefitPlanGrossPrescriptionDrugSubsidyReceiptsReceived
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.5us-gaap_DefinedBenefitPlanGrossPrescriptionDrugSubsidyReceiptsReceived
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
汇率增益 (3.7)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(8.0)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
福利义务-年底 (395.9)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(356.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(459.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年初 251.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
237.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
计划资产的实际收益 31.9us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
11.0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
26.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
参与者的贡献 0.8clf_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
1.8clf_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
雇主贡献 6.9us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
20.7us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
福利支付 (22.1)clf_DefinedBenefitPlanPlanAssetsBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(18.7)clf_DefinedBenefitPlanPlanAssetsBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
汇率增益 0us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
计划资产的公允价值-年末 269.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
251.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
237.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 269.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
251.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
237.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
固定收益计划,收益义务 (395.9)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(356.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(459.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
计划资金不足 (126.6)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(104.4)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
12月31日确认的金额 (126.6)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(104.4)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
财务状况表确认的金额:      
流动负债 (6.8)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(7.9)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
非流动负债 (119.8)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(96.5)us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
确认净额 (126.6)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(104.4)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
累计其他综合收益确认的金额:      
前期服务成本 (42.9)us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(45.4)us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
净精算损失 97.1us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
67.0us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
确认净额 54.2us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
21.6us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
预计2013年其他累计综合收益摊销为定期福利净成本的金额:      
净精算损失 6.3us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
前期服务成本 (3.7)us-gaap_DefinedBenefitPlanFutureAmortizationOfPriorServiceCostCredit
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
确认净额 2.6us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
固定收益计划,因缩减而确认的净收益(损失) (8.8)us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
固定收益计划,特殊终止福利 0us-gaap_DefinedBenefitPlanSpecialTerminationBenefits
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanSpecialTerminationBenefits
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
受薪雇员[会员]|退休金福利[会员]      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年底 (471.4)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
(427.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年末 366.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
357.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 366.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
357.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
固定收益计划,收益义务 (471.4)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
(427.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
计划资金不足 (105.0)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
(69.8)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
受薪雇员[会员]b|其他福利[会员]      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年底 (54.0)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
(53.6)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年末 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
固定收益计划,收益义务 (54.0)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
(53.6)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
计划资金不足 (54.0)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
(53.6)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SalariedEmployeesMember
 
小时工[会员]|养老金福利[会员]      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年底 (739.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
(674.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年末 576.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
552.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 576.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
552.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
固定收益计划,收益义务 (739.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
(674.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
计划资金不足 (162.6)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
(122.1)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
小时工【会员】|其他福利【会员】      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年底 (341.9)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
(302.6)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年末 269.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
251.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 269.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
251.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
固定收益计划,收益义务 (341.9)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
(302.6)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
 
计划资金不足 (72.6)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_HourlyEmployeesMember
(50.8)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
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矿业雇员[会员]b|养老金福利[会员]      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年底 (9.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
(6.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
 
设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年末 6.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
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/ us-gaap_TitleOfIndividualAxis
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5.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
 
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 6.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
5.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
 
固定收益计划,收益义务 (9.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
(6.8)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
 
计划资金不足 (2.6)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
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(1.6)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_MiningEmployeesMember
 
行政人员补充退休计划S E R P[会员]|退休金福利[会员]      
设定受益计划,利益义务变更[向前滚动]      
福利义务-年底 (7.6)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
(9.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
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设定受益计划,计划资产公允价值变动[前滚]      
计划资产的公允价值-年末 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
 
截至12月31日资金情况:      
设定受益计划,计划资产的公允价值 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
 
固定收益计划,收益义务 (7.6)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
(9.2)us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
 
计划资金不足 (7.6美元)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember
(9.2美元)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
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= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_TitleOfIndividualAxis
= clf_SupplementalExecutiveRetirementPlanSERPMember