Employee Benefit Plans (Schedule Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,736	$ 2,448
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	152	261
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	152	261
Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	540	750
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	540	750
Common collective trust funds - International equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137	363
Common collective trust funds - U.S. equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	351	327
Debt instruments - Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	406	601
Debt instruments - Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	406	601
Debt instruments - U.S. Treasury instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	112	98
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	112	98
Debt instruments - U.S. government agency, state and local government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31	29
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	31	29
Other Debt Instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	19
Other Debt Instruments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	19
Fair Value, Measurements, Recurring [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,248	1,758
Fair Value, Measurements, Recurring [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	804	1,109
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 444	$ 649