Employee Benefit Plans (Expected Future Benefit Payments To Be Paid) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 105
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	112
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	118
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	125
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	132
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	762
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	12
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	12
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	12
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	12
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	11
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 54