Annual report pursuant to Section 13 and 15(d)

Postretirement Health Care and Life Insurance Benefits (Estimated Postretirement Benefit Payments In Future Years) (Details)

v2.4.1.9
Postretirement Health Care and Life Insurance Benefits (Estimated Postretirement Benefit Payments In Future Years) (Details) (Other Postretirement Benefit Plan [Member], USD $)
In Millions, unless otherwise specified
Jan. 31, 2015
Other Postretirement Benefit Plan [Member]
 
Expected Benefit  
2015 $ 21us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2016 20us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2017 19us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2018 19us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2019 18us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2020-2024 79us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Expected Federal Subsidy  
2015 1us-gaap_PrescriptionDrugSubsidyReceiptsNextTwelveMonths
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2016 1us-gaap_PrescriptionDrugSubsidyReceiptsYearTwo1
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2017 1us-gaap_PrescriptionDrugSubsidyReceiptsRollingYearThree
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2018 1us-gaap_PrescriptionDrugSubsidyReceiptsYearFour1
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2019 1us-gaap_PrescriptionDrugSubsidyReceiptsYearFive1
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
2020-2024 $ 3us-gaap_PrescriptionDrugSubsidyReceiptsAfterYearFive
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember