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Annual report pursuant to Section 13 and 15(d)

PENSION AND OTHER POSTRETIREMENT BENEFITS (Effect of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) on Changes in Other Benefit Plan Assets) (Details)

v2.4.1.9
PENSION AND OTHER POSTRETIREMENT BENEFITS (Effect of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) on Changes in Other Benefit Plan Assets) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year $ 188.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets $ 200.5us-gaap_DefinedBenefitPlanFairValueOfPlanAssets Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 15.9us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld 41.0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld Ìý
Acquired through business combinations 6.8us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets 145.0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets Ìý
Sales (7.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets (172.8)us-gaap_DefinedBenefitPlanDivestituresPlanAssets Ìý
Fair value of plan assets — end of year 205.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 188.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets Ìý
Hedge Funds [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year 57.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		85.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 3.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		4.5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		Ìý
Acquired through business combinations 0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		66.0us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		Ìý
Sales 0us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		(97.3)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		Ìý
Fair value of plan assets — end of year 59.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		57.6us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember 		Ìý
Private Equity Funds [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year 29.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		29.3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 3.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		(2.1)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		Ìý
Acquired through business combinations 1.4us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		14.7us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		Ìý
Sales (5.5)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		(18.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		Ìý
Fair value of plan assets — end of year 31.2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		29.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember 		Ìý
Real Estate [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year 40.9us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		29.4us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 5.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		5.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		Ìý
Acquired through business combinations 5.4us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		36.8us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		Ìý
Sales (1.5)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		(30.0)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		Ìý
Fair value of plan assets — end of year 50.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		40.9us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_RealEstateMember 		Ìý
Other Benefits [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year Ìý Ìý 237.0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Actual return on plan assets: Ìý Ìý Ìý
Fair value of plan assets — end of year 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
Other Benefits [Member] | Hedge Funds [Member] Ìý Ìý Ìý
Actual return on plan assets: Ìý Ìý Ìý
Fair value of plan assets — end of year 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 		Ìý
Other Benefits [Member] | Private Equity Funds [Member] Ìý Ìý Ìý
Actual return on plan assets: Ìý Ìý Ìý
Fair value of plan assets — end of year 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 		Ìý
Other Benefits [Member] | Structured Credit [Member] Ìý Ìý Ìý
Actual return on plan assets: Ìý Ìý Ìý
Fair value of plan assets — end of year 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 		Ìý
Other Benefits [Member] | Real Estate [Member] Ìý Ìý Ìý
Actual return on plan assets: Ìý Ìý Ìý
Fair value of plan assets — end of year 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 		Ìý
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year 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 		Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 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 		Ìý
Acquired through business combinations 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 		Ìý
Sales (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 		Ìý
Fair value of plan assets — end of year 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 		Ìý
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Hedge Funds [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year 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 		Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 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 		Ìý
Acquired through business combinations 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 		Ìý
Sales (14.2)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		(22.5)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_HedgeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		Ìý
Fair value of plan assets — end of year 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 		Ìý
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Private Equity Funds [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
Fair value of plan assets — beginning of year 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 		Ìý
Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 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 		Ìý
Acquired through business combinations 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 		Ìý
Sales (1.3)us-gaap_DefinedBenefitPlanDivestituresPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_PrivateEquityFundsMember
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= 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 		Ìý
Fair value of plan assets — end of year 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
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Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Structured Credit [Member] Ìý Ìý Ìý
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Ìý Ìý Ìý
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Actual return on plan assets: Ìý Ìý Ìý
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Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Real Estate [Member] Ìý Ìý Ìý
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Actual return on plan assets: Ìý Ìý Ìý
Relating to assets still held at the reporting date 0.9us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
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