Annual report pursuant to Section 13 and 15(d)

PENSION AND OTHER POSTRETIREMENT BENEFITS (Details 4)

v2.4.1.9
PENSION AND OTHER POSTRETIREMENT BENEFITS (Details 4) (USD $)
In Millions, unless otherwise specified
 1 Months Ended
Jul. 31, 2012
Dec. 31, 2013
Dec. 31, 2014
Dec. 31, 2012
Pension and other postretirement benefits        
US Pension Fair Value Reclassified from Level 1 to Level 2   $ 683cmi_USPensionFairValueReclassifiedfromLevel1toLevel2    
U.S. Plans        
Pension and other postretirement benefits        
Fair Value of Plan Assets   2,445us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember 		2,713us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember 		2,327us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Pending trade purchases/sales   (28)cmi_PendingTradePurchasesSales
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember 		5cmi_PendingTradePurchasesSales
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember 		 
Accruals   8us-gaap_AccruedInvestmentIncomeReceivable
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember 		[1] 9us-gaap_AccruedInvestmentIncomeReceivable
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U.S. Plans | Quoted prices in active markets for identical assets (Level 1)        
Pension and other postretirement benefits        
Fair Value of Plan Assets   272us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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U.S. Plans | Quoted prices in active markets for identical assets (Level 1) | U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   96us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel1Member 		[2] 103us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member 		 
U.S. Plans | Quoted prices in active markets for identical assets (Level 1) | Non-U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   143us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel1Member 		[2] 137us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel1Member 		 
U.S. Plans | Quoted prices in active markets for identical assets (Level 1) | Net cash equivalents        
Pension and other postretirement benefits        
Fair Value of Plan Assets   33us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
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/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member 		[2],[3] 28us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
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= us-gaap_FairValueInputsLevel1Member 		[3]  
U.S. Plans | Significant other observable inputs (Level 2)        
Pension and other postretirement benefits        
Fair Value of Plan Assets   1,897us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		[2] 2,125us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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U.S. Plans | Significant other observable inputs (Level 2) | U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   387us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel2Member 		 
U.S. Plans | Significant other observable inputs (Level 2) | Non-U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   126us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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U.S. Plans | Significant other observable inputs (Level 2) | Government debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   780us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel2Member 		 
U.S. Plans | Significant other observable inputs (Level 2) | U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   523us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
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= us-gaap_DomesticCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
U.S. Plans | Significant other observable inputs (Level 2) | Non-U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   64us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_ForeignCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		[2] 87us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_ForeignCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
U.S. Plans | Significant other observable inputs (Level 2) | Asset/mortgaged backed securities        
Pension and other postretirement benefits        
Fair Value of Plan Assets   12us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
U.S. Plans | Significant other observable inputs (Level 2) | Net cash equivalents        
Pension and other postretirement benefits        
Fair Value of Plan Assets   3us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
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= us-gaap_FairValueInputsLevel2Member 		[3]  
U.S. Plans | Significant other observable inputs (Level 2) | Derivative instruments        
Pension and other postretirement benefits        
Fair Value of Plan Assets   2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_DerivativeMember
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= us-gaap_FairValueInputsLevel2Member 		[2],[4] 2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_DerivativeMember
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
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= us-gaap_FairValueInputsLevel2Member 		[4]  
U.S. Plans | Significant unobservable inputs (Level 3)        
Pension and other postretirement benefits        
Fair Value of Plan Assets   296us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		306us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		286us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
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= us-gaap_FairValueInputsLevel3Member
U.S. Plans | Significant unobservable inputs (Level 3) | Private equity and real estate        
Pension and other postretirement benefits        
Fair Value of Plan Assets   296us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel3Member 		[5] 306us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_FairValueInputsLevel3Member 		[5]  
U.S. Plans | Total        
Pension and other postretirement benefits        
Fair Value of Plan Assets   2,465us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   483us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | Non-U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   269us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | Government debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   780us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   523us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | Non-U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   64us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | Asset/mortgaged backed securities        
Pension and other postretirement benefits        
Fair Value of Plan Assets   12us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
U.S. Plans | Total | Net cash equivalents        
Pension and other postretirement benefits        
Fair Value of Plan Assets   36us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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U.S. Plans | Total | Derivative instruments        
Pension and other postretirement benefits        
Fair Value of Plan Assets   2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
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= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[4] 2us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_DerivativeMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[4]  
U.S. Plans | Total | Private equity and real estate        
Pension and other postretirement benefits        
Fair Value of Plan Assets   296us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_PrivateEquityAndRealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[5] 306us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_PrivateEquityAndRealEstateMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[5]  
Non-U.S. Plans        
Pension and other postretirement benefits        
Fair Value of Plan Assets   1,516us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember 		1,724us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember 		1,324us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
Non-U.S. Plans | Insurance contract        
Pension and other postretirement benefits        
Payment deferment period 10 years      
Non-U.S. Plans | Quoted prices in active markets for identical assets (Level 1)        
Pension and other postretirement benefits        
Fair Value of Plan Assets   13us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member 		24us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member 		 
Non-U.S. Plans | Quoted prices in active markets for identical assets (Level 1) | Net cash equivalents        
Pension and other postretirement benefits        
Fair Value of Plan Assets   13us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member 		[3] 24us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member 		[3]  
Non-U.S. Plans | Significant other observable inputs (Level 2)        
Pension and other postretirement benefits        
Fair Value of Plan Assets   946us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		1,096us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
Non-U.S. Plans | Significant other observable inputs (Level 2) | U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   270us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		153us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
Non-U.S. Plans | Significant other observable inputs (Level 2) | Non-U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   328us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesNonUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		399us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesNonUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
Non-U.S. Plans | Significant other observable inputs (Level 2) | Government debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   120us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		   
Non-U.S. Plans | Significant other observable inputs (Level 2) | U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets     321us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_DomesticCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
Non-U.S. Plans | Significant other observable inputs (Level 2) | Non-U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   138us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_ForeignCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		158us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_ForeignCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
Non-U.S. Plans | Significant other observable inputs (Level 2) | Derivative instruments        
Pension and other postretirement benefits        
Fair Value of Plan Assets   24us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_DerivativeMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		[6]    
Non-U.S. Plans | Significant other observable inputs (Level 2) | Re-insurance        
Pension and other postretirement benefits        
Fair Value of Plan Assets   66us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_ReinsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		65us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_ReinsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member 		 
Non-U.S. Plans | Significant unobservable inputs (Level 3)        
Pension and other postretirement benefits        
Fair Value of Plan Assets   557us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		604us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		486us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Non-U.S. Plans | Significant unobservable inputs (Level 3) | Insurance contract        
Pension and other postretirement benefits        
Fair Value of Plan Assets   440us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_InsuranceContractMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		462us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_InsuranceContractMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		 
Non-U.S. Plans | Significant unobservable inputs (Level 3) | Private equity, real estate and insurance        
Pension and other postretirement benefits        
Fair Value of Plan Assets   557us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_PrivateEquityRealEstateAndInsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		[5] 604us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_PrivateEquityRealEstateAndInsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member 		[5]  
Non-U.S. Plans | Total        
Pension and other postretirement benefits        
Fair Value of Plan Assets   1,516us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		1,724us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
Non-U.S. Plans | Total | U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   270us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		153us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
Non-U.S. Plans | Total | Non-U.S. Equity        
Pension and other postretirement benefits        
Fair Value of Plan Assets   328us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesNonUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		399us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_EquitySecuritiesNonUSMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
Non-U.S. Plans | Total | Government debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   120us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_USTreasuryAndGovernmentMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		   
Non-U.S. Plans | Total | U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets     321us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_DomesticCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
Non-U.S. Plans | Total | Non-U.S. Corporate debt        
Pension and other postretirement benefits        
Fair Value of Plan Assets   138us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_ForeignCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		158us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_ForeignCorporateDebtSecuritiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
Non-U.S. Plans | Total | Net cash equivalents        
Pension and other postretirement benefits        
Fair Value of Plan Assets   13us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[3] 24us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_CashEquivalentsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[3]  
Non-U.S. Plans | Total | Derivative instruments        
Pension and other postretirement benefits        
Fair Value of Plan Assets   24us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_DerivativeMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[6]    
Non-U.S. Plans | Total | Re-insurance        
Pension and other postretirement benefits        
Fair Value of Plan Assets   66us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_ReinsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		65us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_ReinsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		 
Non-U.S. Plans | Total | Private equity, real estate and insurance        
Pension and other postretirement benefits        
Fair Value of Plan Assets   $ 557us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_PrivateEquityRealEstateAndInsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[5] $ 604us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= cmi_PrivateEquityRealEstateAndInsuranceMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_ForeignPensionPlansDefinedBenefitMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember 		[5]  
[1] Interest or dividends that had not been settled as of the year ended December 31.
[2] We revised 2013 balances to classify $683 million as Level 2 assets instead of Level 1.
[3] Cash equivalents include commercial paper, short-term government/agency, mortgage and credit instruments.
[4] Derivative instruments include interest rate swaps and credit default swaps.
[5] The instruments in private equity and real estate funds, for which quoted market prices are not available, are valued at their estimated fair value as determined by applicable investment managers or by audited financial statement of the funds.
[6] Derivative instruments consist of interest rate swaps.