Retirement-Related Benefits - All Retirement Plans Cost (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2019 |
Jun. 30, 2020 |
Jun. 30, 2019 |
|
| Retirement-Related Benefits | ||||
| Defined benefit and contribution pension plans - cost | $ 596 | $ 441 | $ 1,179 | $ 878 |
| Nonpension postretirement plans - cost | 50 | 53 | 102 | 107 |
| Total | $ 645 | $ 494 | $ 1,281 | $ 985 |
| Year-to-year percent change, defined benefit and contribution pension plans cost (as a percent) | 34.90% | 34.30% | ||
| Year-to-year percent change, nonpension postretirement plans cost (as a percent) | (5.60%) | (4.80%) | ||
| Year-to-year percent change, total (as a percent) | 30.60% | 30.00% | ||