Employee Benefit Plans (Schedule Of Estimated Benefits Expected To Be Paid) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	$ 739
2018	781
2019	821
2020	857
2021	892
Thereafter in the succeeding five years	4,879
Employer contribution	334	$ 334
Expected employer contribution next year	327
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	87
2018	93
2019	97
2020	103
2021	108
Thereafter in the succeeding five years	592
Employer contribution	52	$ 61
Expected employer contribution next year	61
Federal Subsidy [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	(8)
2018	(9)
2019	(10)
2020	(10)
2021	(11)
Thereafter in the succeeding five years	$ (15)