Pension, OPEB and Savings Plans (Amounts Expected To Be Amortized From Accumulated OCL, Regulatory Assets And Deferred Assets Into Net Periodic Benefit Cost) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial (Gain) Loss	$ 97
Prior Service Cost	(18)
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial (Gain) Loss	51
Prior Service Cost	$ (11)