Employee Benefit Plans Level 4 Benefit Payments (Details) $ in Millions	Dec. 31, 2016 USD ($)
Pension Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Rolling Maturity [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	$ 333
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	339
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	346
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	353
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	352
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	1,748
Net Defined Benefit Plan Expected Future Benefit Payments	(3,471)
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Rolling Maturity [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	33
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	30
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	27
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	24
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	22
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	82
Net Defined Benefit Plan Expected Future Benefit Payments	$ (218)