v3.20.2
Pension And Postretirement Benefits (Pension And Postretirement Benefit Costs Included In Operating Expenses) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]        
Actuarial (gain) loss     $ 0 $ 2,131
Qualified Plan [Member] | Funded Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Net (credit) cost $ (749) $ 1,268 (1,496) 1,327
Pension Benefit [Member] | Qualified Plan [Member] | Funded Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost - benefits earned during the period 258 243 515 483
Interest cost on benefit obligation 422 508 844 1,057
Expected return on assets (890) (880) (1,779) (1,731)
Amortization of prior service credit (29) (24) (57) (57)
Actuarial (gain) loss 0 1,699 0 2,131
Net (credit) cost (239) 1,546 (477) 1,883
Postretirement Benefit [Member] | Qualified Plan [Member] | Funded Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost - benefits earned during the period 13 18 26 36
Interest cost on benefit obligation 104 186 208 372
Expected return on assets (45) (56) (89) (112)
Amortization of prior service credit (582) (426) (1,164) (852)
Net (credit) cost $ (510) $ (278) $ (1,019) $ (556)