| **Postretirement Benefits - Narrative (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended                                                                                                                                                 | 6 Months Ended                                                                                                                                                 |
|--------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| **Defined Benefit Plan Disclosure [Line Items]**                                                 |                                                                                                                                                           |                                                                                                                                                           |   |   |
| Restructuring charges                                                                            | $ 6us-gaap_RestructuringCharges                                                                                                                                | $ 8us-gaap_RestructuringCharges                                                                                                                                | $ 9us-gaap_RestructuringCharges | $ 11us-gaap_RestructuringCharges |
| Defined Contribution Plan, Cost Recognized                                                       | 8us-gaap_DefinedContributionPlanCostRecognized                                                                                                                 | 7us-gaap_DefinedContributionPlanCostRecognized                                                                                                                 | 17us-gaap_DefinedContributionPlanCostRecognized | 15us-gaap_DefinedContributionPlanCostRecognized |
| Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year            |                                                                                                                                                           |                                                                                                                                                           | 51us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear |   |
| Pension Benefits                                                                                 |                                                                                                                                                           |                                                                                                                                                           |   |   |
| **Defined Benefit Plan Disclosure [Line Items]**                                                 |                                                                                                                                                           |                                                                                                                                                           |   |   |
| Employer contributions                                                                           | $ 32us-gaap_DefinedBenefitPlanContributionsByEmployer/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis= us-gaap_PensionPlansDefinedBenefitMember | $ 36us-gaap_DefinedBenefitPlanContributionsByEmployer/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis= us-gaap_PensionPlansDefinedBenefitMember | $ 62us-gaap_DefinedBenefitPlanContributionsByEmployer/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis= us-gaap_PensionPlansDefinedBenefitMember | $ 65us-gaap_DefinedBenefitPlanContributionsByEmployer/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis= us-gaap_PensionPlansDefinedBenefitMember |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The increase in the fair value of plan assets from contributions made by the employer.
+ References
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| X                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of the cost recognized during the period for defined contribution plans.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.
+ References
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| X                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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