v3.10.0.1
Pension and Postretirement Benefit Plans and Defined Contribution Plans - One-Percentage-Point Increase or Decrease in the Healthcare Cost Trend Rate (Details) - Postretirement Benefits Plan [Member]
$ in Millions
12 Months Ended
Dec. 31, 2018
USD ($)
Defined Benefit Plan Disclosure [Line Items]  
Effect on total service and interest cost components, increase $ 3
Effect on total service and interest cost components, decrease (2)
Effect on postretirement benefit obligation, increase 35
Effect on postretirement benefit obligation, decrease $ (27)