Retirement Plans - Schedule of MTM Adjustments (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
May 31, 2021 |
May 31, 2020 |
May 31, 2019 |
|
| Actuarial Gain Loss By Component Pre Tax [Abstract] | |||
| Actual versus expected return on assets | $ (1,712) | $ (2,024) | $ 476 |
| Discount rate change | (397) | 2,997 | 1,780 |
| Demographic experience: | |||
| Current year actuarial loss | 302 | 50 | 739 |
| Change in future assumptions | 685 | (229) | 887 |
| Curtailment gain on TNT Netherlands pension plan | (54) | ||
| Total MTM (gain) loss | $ (1,176) | $ 794 | $ 3,882 |