Retirement Plans - Schedule of Retirement Plan Costs (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Nov. 30, 2021 |
Nov. 30, 2020 |
Nov. 30, 2021 |
Nov. 30, 2020 |
|
| Pension And Other Postretirement Benefit Expense [Abstract] | ||||
| Defined benefit pension plans, net | $ (2) | $ 27 | $ (5) | $ 52 |
| Defined contribution plans | 171 | 153 | 351 | 311 |
| Postretirement healthcare plans | 23 | 20 | 45 | 41 |
| Retirement plans MTM net loss | 260 | 52 | 260 | 52 |
| Retirement plans costs | $ 452 | $ 252 | $ 651 | $ 456 |