Pension, OPEB and Savings Plans (Reconciliations Of The Beginning And Ending Balances Of Pension And OPEB Plans' Level 3 Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year		$ 5,654
Fair Value of Assets at End of Year		5,413		$ 5,654
Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year		25
Fair Value of Assets at End of Year		19		25
Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	[1]	25
Fair Value of Assets at End of Year	[1]	19		25
Private Equity [Member] | Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year		25	[1]	25
Purchases/(Sales)		(10)		(5)
Transfer In/ (Out)		0		0
Actual Return on Asset Sales		1		3
Actual Return on Assets Still Held		3		2
Fair Value of Assets at End of Year	[1]	$ 19		$ 25

[1] Investments in fixed income securities including bond funds are priced using an evaluated pricing approach or the most recent exchange or quoted bid (primarily Level 2).