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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss			$ 63	$ 4,048
Qualified Plan | Funded Plan
Defined Benefit Plan Disclosure [Line Items]
Net (credit) cost	$ (747)	$ 1,400	(2,243)	2,727
Pension Cost | Qualified Plan | Funded Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	257	260	772	743
Interest cost on projected / accumulated postretirement benefit obligation	421	463	1,265	1,520
Expected return on assets	(888)	(905)	(2,667)	(2,636)
Amortization of prior service credit	(28)	(28)	(85)	(85)
Actuarial (gain) loss	0	1,888	0	4,019
Net (credit) cost	(238)	1,678	(715)	3,561
Postretirement Cost | Qualified Plan | Funded Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	14	19	40	55
Interest cost on projected / accumulated postretirement benefit obligation	104	185	312	557
Expected return on assets	(44)	(57)	(133)	(169)
Amortization of prior service credit	(583)	(425)	(1,747)	(1,277)
Net (credit) cost	$ (509)	$ (278)	$ (1,528)	$ (834)