Pension and Postretirement Benefit Plans - Narrative (Details) - Funded - USD ($) $ in Millions |
1 Months Ended | 12 Months Ended | |
|---|---|---|---|
Aug. 31, 2015 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| United States | |||
| Benefit Plan Information | |||
| Original percentage medical inflation indexation by company in year | 3.00% | ||
| Revised percentage medical inflation indexation by company in year | 1.50% | ||
| Qualified and Non-qualified Pension Benefits | |||
| Benefit Plan Information | |||
| Company contributions year to date | $ 366 | $ 964 | |
| Qualified and Non-qualified Pension Benefits | United States | |||
| Benefit Plan Information | |||
| Company contributions year to date | 254 | 852 | |
| Qualified and Non-qualified Pension Benefits | International | |||
| Benefit Plan Information | |||
| Company contributions year to date | 112 | 112 | |
| Postretirement Benefits | |||
| Benefit Plan Information | |||
| Company contributions year to date | $ 4 | $ 3 | |