Income Taxes (Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] | |||
| Balance at beginning of year | $ 37 | $ 13 | $ 27 |
| Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions | 2 | 25 | 0 |
| Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions | 0 | 0 | 11 |
| Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions | (25) | 0 | (13) |
| Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities | (1) | 0 | (11) |
| Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations | (1) | (1) | (1) |
| Balance at end of year | $ 12 | $ 37 | $ 13 |