| **Restructuring and Impairments - Narrative (Details) - USD ($) $ in Millions**           | 3 Months Ended | 6 Months Ended |        |
|-------------------------------------------------------------------------------------------|----------------|----------------|--------|
||
| **Restructuring Cost and Reserve [Line Items]**                                           |           |           |   |   |   |   |   |
| Restructuring charges                                                                     | $ 3            | $ 6            |   |   | $ 6 | $ 9 |   |
| Asset impairment charges                                                                  | 3              | 1              |   |   | 5 | 8 |   |
| Goodwill                                                                                  | 38             |           |   |   | 38 |   | $ 38 |
| North America Truck [Member]                                                              |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                           |           |           |   |   |   |   |   |
| Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)                    |           |           | $ 7    |   |   |   |   |
| Indianapolis and Waukesha Foundry [Member] | North America Truck [Member]                 |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                           |           |           |   |   |   |   |   |
| Restructuring and Related Cost, Cost Incurred to Date                                     |           | $ 12           | $ 13   |   |   | $ 12 |   |
| Minimum [Member] | Chatham [Member] | North America Truck [Member]                        |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                           |           |           |   |   |   |   |   |
| Restructuring and Related Cost, Expected Cost                                             | 0              |           |   |   | 0 |   |   |
| Maximum [Member] | Chatham [Member] | North America Truck [Member]                        |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                           |           |           |   |   |   |   |   |
| Restructuring and Related Cost, Expected Cost                                             | $ 60           |           |   |   | $ 60 |   |   |
| Other Postretirement Benefit Plan [Member] | Chatham [Member] | Facility Closing [Member] |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                           |           |           |   |   |   |   |   |
| Postemployment Benefits, Period Expense                                                   |           |           |   | $ 14 |   |   |   |

| 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 after accumulated impairment loss of an asset representing 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 impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.
+ References
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| - Definition
Period expense related to postemployment benefits.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of costs incurred to date for the specified restructuring cost.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount expected to be recognized in earnings for the specified restructuring cost.
+ 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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