v3.20.4
Employee Benefit Plans (Information About The Expected Cash Flows For The Qualified and Non-Qualified Pension Plans) (Details)
Dec. 31, 2020
USD ($)
Qualified Plan [Member] | Pension Plan [Member]  
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]  
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year $ 0
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]  
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 138,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Two 138,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Three 136,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Four 138,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Five 137,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter 673,000,000
Nonqualified Plan [Member] | Supplemental Employee Retirement Plan [Member]  
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]  
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year 33,000,000
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]  
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 33,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Two 31,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Three 15,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Four 11,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Five 12,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter $ 57,000,000