v3.20.4
Employee Benefit Plans (Components Of Net Periodic Pension Costs) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]      
Service cost $ 39 $ 31 $ 38
Interest cost 68 80 75
Expected return on plan assets (148) (137) (153)
Amortization of actuarial loss 47 41 36
Settlement charge 0 2 0
Net periodic pension (benefit) cost 6 17 (4)
Qualified Plan [Member] | Pension Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 34 28 35
Interest cost 64 75 70
Expected return on plan assets (148) (137) (153)
Amortization of actuarial loss 39 36 31
Settlement charge 0 0 0
Net periodic pension (benefit) cost (11) 2 (17)
Nonqualified Plan [Member] | Supplemental Employee Retirement Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 5 3 3
Interest cost 4 5 5
Expected return on plan assets 0 0 0
Amortization of actuarial loss 8 5 5
Settlement charge 0 2 0
Net periodic pension (benefit) cost $ 17 $ 15 $ 13