Employee Benefit Plans (Schedule Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	$ 2,131	$ 1,922
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	1,020	875
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	1,111	1,047
Common stock - U.S. companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	222	196
Common stock - U.S. companies [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	222	196
Common stock - International companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	2	8
Common stock - International companies [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	2	8
Equity mutual funds - Emerging markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	82	58
Equity mutual funds - Emerging markets [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	82	58
Equity mutual funds - International [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	117	105
Equity mutual funds - International [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	117	105
Equity mutual funds - Large cap U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	447	409
Equity mutual funds - Large cap U.S. [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	447	409
Common collective trust funds - International equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	306	278
Common collective trust funds - International equity [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	306	278
Common collective trust funds - Large cap U.S. equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	47	45
Common collective trust funds - Large cap U.S. equity [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	47	45
Common collective trust funds - Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	190	193
Common collective trust funds - Fixed income [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	190	193
Common collective trust funds - Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	50	47
Common collective trust funds - Other [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	50	47
Debt instruments - Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	492	457
Debt instruments - Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	492	457
Debt instruments - U.S. Treasury instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	150	99
Debt instruments - U.S. Treasury instruments [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	150	99
Debt instruments - U.S. government agency, state and local government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	22	24
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]
Total assets at fair value	22	24
Other Debt Instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	4	3
Other Debt Instruments [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets at fair value	$ 4	$ 3