| **Employee Retirement Benefits (Reconciliation Of The Funded Status For Qualified Plan And SERP) (Details) - USD ($) $ in Millions** | Dec. 31, 2017 | Dec. 31, 2016 |
|--------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Retirement Benefits [Abstract]**                                                                                                   |          |          |
| Other liabilities                                                                                                                    | $ (6)         | $ (25)        |
| Total                                                                                                                                | (6)           | (25)          |
| **Pension amounts recognized in accumulated other comprehensive income:**                                                            |          |          |
| Net actuarial loss                                                                                                                   | 12            | 26            |
| Prior service cost                                                                                                                   | 0             | 0             |
| Total                                                                                                                                | $ 12          | $ 26          |

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Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).
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| - Definition
Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.
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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).
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Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.
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| - Definition
Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans.
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