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退休金及其他退休后福利（第3级不可观察输入）（详情）

v2.4.1.9
养老金和其他退休后福利养老金和其他退休后福利（不可观察输入，第3级）（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
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 205.8美元us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 188.6美元us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 200.5美元us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
设定受益计划，仍持有计划资产的实际回报 15.9us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld 41.0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld  
固定收益计划，当期出售计划资产的实际回报 1.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod (25.1)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod  
固定收益计划，企业合并和收购，计划资产 6.8us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets 145.0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets  
固定收益计划，资产剥离，计划资产 (7.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets (172.8)us-gaap_DefinedBenefitPlanDivestituresPlanAssets  
其他退休福利计划、设定受益计划〔成员〕      
设定受益计划及其他退休后福利计划表      
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
私募股权基金〔成员〕      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 31.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		29.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		29.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
设定受益计划，仍持有计划资产的实际回报 3.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		(2.1)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		 
固定收益计划，当期出售计划资产的实际回报 3.0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		5.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		 
固定收益计划，企业合并和收购，计划资产 1.4us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		14.7us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		 
固定收益计划，资产剥离，计划资产 (5.5)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		(18.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		 
私募股权基金[成员]b|其他退休福利计划、设定受益计划[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 6.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		6.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		 
结构性融资〔委员〕      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 65.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		61.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		56.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember
设定受益计划，仍持有计划资产的实际回报 4.4us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		33.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		 
固定收益计划，当期出售计划资产的实际回报 0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		(28.7)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		 
固定收益计划，企业合并和收购，计划资产 0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		27.5us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		 
固定收益计划，资产剥离，计划资产 0us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		(27.5)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_StructuredFinanceMember 		 
房地产〔成员〕      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 50.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		40.9us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		29.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
设定受益计划，仍持有计划资产的实际回报 5.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		5.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		 
固定收益计划，当期出售计划资产的实际回报 0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		(0.4)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		 
固定收益计划，企业合并和收购，计划资产 5.4us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		36.8us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		 
固定收益计划，资产剥离，计划资产 (1.5)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		(30.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		 
房地产[成员]b|其他退休福利计划、设定受益计划[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 8.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		13.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		 
结构性信贷[成员]|其他退休福利计划、设定受益计划[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 6.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		13.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		 
对冲基金〔成员〕      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 59.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		57.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		85.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
设定受益计划，仍持有计划资产的实际回报 3.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		4.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		 
固定收益计划，当期出售计划资产的实际回报 (1.5)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		(1.2)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		 
固定收益计划，企业合并和收购，计划资产 0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		66.0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		 
固定收益计划，资产剥离，计划资产 0us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		(97.3)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		 
对冲基金[成员]b|其他退休福利计划，固定收益计划[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 11.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		24.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember 		 
公允价值，投入，第3级[成员]|其他退休后福利计划，设定受益[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 32.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		57.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		57.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
设定受益计划，仍持有计划资产的实际回报 2.8us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		7.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，当期出售计划资产的实际回报 1.9us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(2.4)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，企业合并和收购，计划资产 0.1us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		48.0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，资产剥离，计划资产 (29.6)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(53.6)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
公允价值，投入，第3级[成员]私募股权基金[成员]|其他退休福利计划，设定受益[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 6.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		6.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		6.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
设定受益计划，仍持有计划资产的实际回报 1.0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		0.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，当期出售计划资产的实际回报 0.4us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		0.4us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，企业合并和收购，计划资产 0.1us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		0.3us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，资产剥离，计划资产 (1.3)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(1.1)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
公允价值，投入，第3级【会员】|房地产【会员】|其他退休后福利计划，设定福利【会员】      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 8.7us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		13.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		15.9us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
设定受益计划，仍持有计划资产的实际回报 0.9us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		2.8us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，当期出售计划资产的实际回报 0.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(0.7)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，企业合并和收购，计划资产 0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		14.2us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，资产剥离，计划资产 (5.9)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(19.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
公允价值，投入，第3级[成员]|结构性信贷[成员]|其他退休后福利计划，确定受益[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 6.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		13.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		12.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
设定受益计划，仍持有计划资产的实际回报 0.4us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		2.4us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，当期出售计划资产的实际回报 0.4us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(1.4)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，企业合并和收购，计划资产 0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		11.0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，资产剥离，计划资产 (8.2)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(11.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= clf_StructuredCreditMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
公允价值，投入，第3级[成员]|对冲基金[成员]|其他退休后福利计划，确定福利[成员]      
设定受益计划及其他退休后福利计划表      
设定受益计划，计划资产的公允价值 11.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		24.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		23.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
设定受益计划，仍持有计划资产的实际回报 0.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		2.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，当期出售计划资产的实际回报 0.6us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(0.7)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，企业合并和收购，计划资产 0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		22.5us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
固定收益计划，资产剥离，计划资产 (14.2美元)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(22.5美元)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member