| **Restructuring and Impairments - Restructuring and Impairment Charges (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------------------------------|----------------|-----------------|----------------|-----------------|
||
| **Restructuring Cost and Reserve [Line Items]**                                                                                   |           |            |           |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Goodwill impairment charge                                                                                                        |           | $ 81            | $ 0            | $ 0             |   |   |   |   |   |   |   |   |   |   |   |   | $ (77) | $ (4) | $ 81 |
| Total restructuring charges                                                                                                       |           | 25              | 107            | 82              |   |   |   | 0 | 1 | 10 | 25 | 108 | 92 |   |   |   |   |   |   |
| Total asset impairment charges                                                                                                    | $ 24           | $ 97            | $ 16           | $ 13            | $ 20 | $ 16 | $ 13 | $ 4 | $ 28 | $ 51 |   |   |   | $ 105 | $ 44 | $ 64 |   |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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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