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, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	$ 6,449	[1]
Fair Value of Assets at End of Year	6,921	[1]
Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Assets at Beginning of Year	8	[2]
Fair Value of Assets at End of Year	$ 5	[2]

[1] Excludes net receivables of $10 million and $15 million as of December 31, 2020 and 2019, respectively, which consist of interest, dividends and receivables and payables related to pending securities sales and purchases. In addition, the table excludes cash and foreign currency of $1 million and $5 million as of December 31, 2020 and 2019, respectively.

[2] Private equity investments primarily include various limited partnerships that invest in either operating companies through acquisitions or developing a portfolio of non-U.S. distressed investments to maximize total return on capital. These investments are valued at NAV (or its equivalent) on a quarterly basis and have significant redemption restrictions preventing redemption until fund liquidation and limited ability to sell these investments. Fund liquidation is not expected to occur for several more years. These investments are not included in the fair value hierarchy in accordance with the guidance on NAV practical expedient.