| **Restructuring and Impairments - Restructuring Reserve by Type (Details) - USD ($) $ in Millions** | 3 Months Ended | 9 Months Ended |        |        |
|-----------------------------------------------------------------------------------------------------|----------------|----------------|--------|--------|
||
| **Restructuring Cost and Reserve [Line Items]**                                                     |           |           |   |   |   |   |   |
| Restructuring charges                                                                               | $ 13           | $ 16           |   | $ 22   | $ 27 |   |   |
| Restructuring Reserve                                                                               | 22             | 25             |   | 22     | 25 | $ 20 | $ 34 |
| Restructuring and Related Cost, Incurred Cost                                                       |           |           |   | 19     | 14 |   |   |
| Payments for Restructuring                                                                          |           |           |   | 15     | 21 |   |   |
| Restructuring Reserve, Accrual Adjustment                                                           |           |           |   | (2)    | (2) |   |   |
| Employee Severance [Member]                                                                         |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                     |           |           |   |   |   |   |   |
| Restructuring charges                                                                               | 13             |           | $ 8    |   |   |   |   |
| Restructuring Reserve                                                                               | 16             | 13             |   | 16     | 13 | 8 | 15 |
| Restructuring and Related Cost, Incurred Cost                                                       |           |           |   | 17     | 12 |   |   |
| Payments for Restructuring                                                                          |           |           |   | 7      | 12 |   |   |
| Restructuring Reserve, Accrual Adjustment                                                           |           |           |   | (2)    | (2) |   |   |
| Employee Relocation [Member]                                                                        |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                     |           |           |   |   |   |   |   |
| Restructuring Reserve                                                                               |           | 0              |   |   | 0 |   | 0 |
| Restructuring and Related Cost, Incurred Cost                                                       |           |           |   |   | 1 |   |   |
| Payments for Restructuring                                                                          |           |           |   |   | 1 |   |   |
| Restructuring Reserve, Accrual Adjustment                                                           |           |           |   |   | 0 |   |   |
| Lease Vacancy [Member] [Domain]                                                                     |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                     |           |           |   |   |   |   |   |
| Restructuring Reserve                                                                               | 5              | 13             |   | 5      | 13 | 11 | 18 |
| Restructuring and Related Cost, Incurred Cost                                                       |           |           |   | 0      | 1 |   |   |
| Payments for Restructuring                                                                          |           |           |   | 6      | 6 |   |   |
| Restructuring Reserve, Accrual Adjustment                                                           |           |           |   | 0      | 0 |   |   |
| Other Restructuring [Member]                                                                        |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                     |           |           |   |   |   |   |   |
| Restructuring Reserve                                                                               | 1              | $ (1)          |   | 1      | (1) | $ 1 | $ 1 |
| Restructuring and Related Cost, Incurred Cost                                                       |           |           |   | 2      | 0 |   |   |
| Payments for Restructuring                                                                          |           |           |   | 2      | 2 |   |   |
| Restructuring Reserve, Accrual Adjustment                                                           |           |           |   | 0      | $ 0 |   |   |
| Indianapolis and Waukesha Foundry [Member] | North America Truck [Member] | Maximum [Member]        |           |           |   |   |   |   |   |
| **Restructuring Cost and Reserve [Line Items]**                                                     |           |           |   |   |   |   |   |
| Restructuring charges                                                                               | $ 3            |           |   | $ 28   |   |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of 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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| X                                                                                                                                                                                                                                                                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of any reversal and other adjustment made during the period to the amount of a previously accrued liability for a specified type of restructuring cost, excluding adjustments for costs incurred during the period, costs settled during the period, and foreign currency translation adjustments.
+ References
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