Pension, OPEB and Savings Plans (Pre-Tax Changes Recognized In Accumulated Other Comprehensive Income (Loss), Regulatory Assets And Deferred Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain) Loss in Current Period	$ 136	$ 803
Amortization of Net Actuarial Gain (Loss)	(150)	(56)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	19	18
Total	5	765
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain) Loss in Current Period	(14)	208
Amortization of Net Actuarial Gain (Loss)	(43)	(23)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	14	14
Total	$ (43)	$ 199