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, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain) Loss in Current Period	$ 241	$ 369
Amortization of Net Actuarial Gain (Loss)	(96)	(85)
Prior Service Cost (Credit) in current period	0	0
Amortization of Prior Service Credit	18	18
Total	163	302
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain) Loss in Current Period	39	(145)
Amortization of Net Actuarial Gain (Loss)	(50)	(64)
Prior Service Cost (Credit) in current period	0	(559)
Amortization of Prior Service Credit	128	1
Total	$ 117	$ (767)