| **Summary of Significant Accounting Policies (Foreign Currency Translation) (Details) - USD ($) $ in Millions** | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Derivative [Line Items]**                                                                                     |            |   |   |
| Net gain (loss) on foreign currency forward contracts                                                           | $ 21            | $ (19) | $ (4) |
| Net gain (loss) on foreign currency transactions                                                                | $ (22)          | $ 9 | $ 11 |

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| - 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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| - Definition
Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.
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