Retirement Plans (Details 1) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Nov. 30, 2016 |
Nov. 30, 2015 |
Nov. 30, 2016 |
Nov. 30, 2015 |
|
| Pension and Other Postretirement Benefit Expense [Abstract] | ||||
| Defined benefit pension plans | $ 58 | $ 54 | $ 116 | $ 107 |
| Defined contribution plans | 112 | 103 | 231 | 205 |
| Postretirement healthcare plans | 19 | 20 | 38 | 41 |
| Retirement plans costs | $ 189 | $ 177 | $ 385 | $ 353 |