| **Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions** | 12 Months Ended |
|-------------------------------------------------------------------------|-----------------|
||
| **Valuation and allowance roll forward**                                |            |   |   |
| Beginning balance, January 1                                            | $ 48            | $ 69 |   |
| Ending balance, December 31                                             | 36              | 48 | $ 69 |
| Allowance for doubtful receivables                                      |            |   |   |
| **Valuation and allowance roll forward**                                |            |   |   |
| Beginning balance, January 1                                            | 17              | 16 | 22 |
| Additions charged to costs and expenses                                 | 33              | 15 | 14 |
| Deductions                                                              | (14)            | (14) | (20) |
| Ending balance, December 31                                             | 36              | 17 | 16 |
| Deferred tax valuation allowance                                        |            |   |   |
| **Valuation and allowance roll forward**                                |            |   |   |
| Beginning balance, January 1                                            | 31              | 53 | 56 |
| Additions charged to costs and expenses                                 | 0               | 0 | 0 |
| Deductions                                                              | (31)            | (22) | (3) |
| Ending balance, December 31                                             | $ 0             | $ 31 | $ 53 |

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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
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of valuation and qualifying accounts and reserves.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of decrease in valuation and qualifying accounts and reserves.
+ References
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| X                                                                                                                                                                                                |
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