Pension, OPEB and Savings Plans (Reconciliations Of The Beginning And Ending Balances Of Pension And OPEB Plans' Level 3 Assets) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	$ 5,405	[1]
Fair Value of Assets at End of Year	5,599	[1]
Pension And OPEB Plans Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year		[1]
Fair Value of Assets at End of Year		[1]
Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	19	[2]
Fair Value of Assets at End of Year	$ 16	[2]

[1] Excludes net receivable of $14 million and $8 million at December 31, 2016 and 2015, respectively, which consists of interest and dividend, receivables and payables related to pending securities sales and purchases.

[2] Private equity investments include various limited partnerships that invest in operating companies through acquisitions or developing a portfolio of non-US distressed investments. These investments are valued at NAV on an annual basis and have significant redemption restrictions preventing redemption until fund liquidation and limited ability to sell these investments. These investments have been removed from the fair value hierarchy in accordance with the new guidance on NAV practical expedient.