Pension And Postretirement Benefits (Pension And Postretirement Benefit Costs Included In Operating Expenses) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss					$ (2,726)	$ (259)
Net (credit) cost	$ (233)			$ (286)	(3,488)	(1,004)
Pension Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	270			282	845	846
Interest cost on benefit obligation	551			484	1,542	1,452
Expected return on assets	(761)			(783)	(2,276)	(2,350)
Amortization of prior service credit	(28)			(31)	(87)	(93)
Actuarial (gain) loss	0	$ (1,796)		0	(1,796)	0
Net (credit) cost	32			(48)	(1,772)	(145)
Postretirement Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	27			32	82	107
Interest cost on benefit obligation	196			193	582	617
Expected return on assets	(76)			(81)	(228)	(240)
Amortization of prior service credit	(412)			(382)	(1,222)	(1,084)
Actuarial (gain) loss	0		$ (930)	0	(930)	(259)
Net (credit) cost	$ (265)			$ (238)	$ (1,716)	$ (859)