Pension and Postretirement Benefit Plans and Defined Contribution Plans - Pension Plans in Excess of Plan Assets (Details) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Foreign Plan [Member] | Pension Plan [Member] | ||
| Pension plans with an ABO in excess of plan assets: | ||
| Fair value of plan assets | $ 5,843 | $ 4,514 |
| ABO | 7,960 | 6,286 |
| Pension plans with a PBO in excess of plan assets: | ||
| Fair value of plan assets | 5,947 | 5,432 |
| PBO | 8,503 | 7,571 |
| Qualified Plan [Member] | United States [Member] | Pension Plan [Member] | ||
| Pension plans with an ABO in excess of plan assets: | ||
| Fair value of plan assets | 14,586 | 13,051 |
| ABO | 16,535 | 15,141 |
| Pension plans with a PBO in excess of plan assets: | ||
| Fair value of plan assets | 14,586 | 13,051 |
| PBO | 16,535 | 15,141 |
| Nonqualified Plan [Member] | United States [Member] | U.S. Supplemental (Non-Qualified) Pension Plans [Member] | ||
| Pension plans with an ABO in excess of plan assets: | ||
| ABO | 1,351 | 1,280 |
| Pension plans with a PBO in excess of plan assets: | ||
| PBO | $ 1,351 | $ 1,280 |