Quarterly report pursuant to Section 13 or 15(d)

MARKETABLE SECURITIES (Details)

v2.4.1.9
MARKETABLE SECURITIES (Details) (USD $)
In Millions, unless otherwise specified
Mar. 29, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities    
Cost $ 115us-gaap_AvailableForSaleSecuritiesAmortizedCost $ 92us-gaap_AvailableForSaleSecuritiesAmortizedCost
Gross unrealized gains/(losses) 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainLossBeforeTax 1us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainLossBeforeTax
Estimated fair value 115us-gaap_AvailableForSaleSecurities 93us-gaap_AvailableForSaleSecurities
Significant other observable inputs (Level 2) | Debt mutual funds    
Schedule of Available-for-sale Securities    
Cost 90us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_FixedIncomeFundsMember 		[1] 75us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_FixedIncomeFundsMember 		[1]
Gross unrealized gains/(losses)   1us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainLossBeforeTax
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_FixedIncomeFundsMember 		[1]
Estimated fair value 90us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_FixedIncomeFundsMember 		[1] 76us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_FixedIncomeFundsMember 		[1]
Significant other observable inputs (Level 2) | Equity Funds    
Schedule of Available-for-sale Securities    
Cost 9us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember 		[1] 9us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember 		[1]
Estimated fair value 9us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember 		[1] 9us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember 		[1]
Significant other observable inputs (Level 2) | Bank debentures    
Schedule of Available-for-sale Securities    
Cost 14us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= cmi_BankDebenturesMember 		[1] 6us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= cmi_BankDebenturesMember 		[1]
Estimated fair value 14us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= cmi_BankDebenturesMember 		[1] 6us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= cmi_BankDebenturesMember 		[1]
Significant other observable inputs (Level 2) | Government debt securities-non-U.S.    
Schedule of Available-for-sale Securities    
Cost 2us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_ForeignGovernmentDebtMember 		[1] 2us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_ForeignGovernmentDebtMember 		[1]
Estimated fair value $ 2us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_ForeignGovernmentDebtMember 		[1] $ 2us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_ForeignGovernmentDebtMember 		[1]
[1] The fair value of Level 2 securities is estimated primarily using actively quoted prices for similar instruments from brokers and observable inputs, including market transactions and third-party pricing services. We do not currently have any Level 3 securities, and there were no transfers between Level 2 or 3 during the first three months of 2015 and 2014.