Employee Benefit Plans (Schedule Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date	Dec. 31, 2019
Fair value of plan assets	$ 2,018	$ 1,736
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	187	152
Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	187	152
Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	575	540
Mutual Fund [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	575	540
Common collective trust funds - International equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	281	137
Common collective trust funds - U.S. equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	391	351
Debt instruments - Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	249	406
Debt instruments - Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	249	406
Debt instruments - U.S. Treasury instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	322	112
Debt instruments - U.S. Treasury instruments [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	322	112
Debt instruments - U.S. government agency, state and local government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	31
Debt instruments - U.S. government agency, state and local government bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	31
Other Debt Instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	7
Other Debt Instruments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	7
Fair Value, Recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,346	1,248
Fair Value, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,084	804
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 262	$ 444