| **Income Taxes (Narrative) (Details) - USD ($) $ in Millions** | 3 Months Ended | 6 Months Ended |
|----------------------------------------------------------------|----------------|----------------|
||
| **Income Tax Disclosure [Abstract]**                           |           |           |   |   |
| Tax at statutory rate, percentage                              | 35.00%         | 35.00%         | 35.00% | 35.00% |
| Excess tax benefit, ASU 2016-09                                | $ 6            |           | $ 6 |   |
| Effect of excess tax benefit, ASU 2016-09, percent             |           |           | 1.50% |   |

| X                                                                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Percent
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of domestic federal statutory tax rate applicable to pretax income (loss).
+ References
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| X                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
No definition available.
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