Benefit Plans (Carrying Value And Fair Market Value Of The Deferred Compensation Obligation for Company Stock Account) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Carrying value of deferred compensation obligation	$ 11	$ 10
Fair market value of deferred compensation obligation	$ 20	$ 21

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