Retirement Plans (Details 3) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Aug. 31, 2015 |
Aug. 31, 2014 |
|
| Pension Plans Contributions [Abstract] | ||
| Required U.S. pension plan contributions | $ 6 | $ 82 |
| Voluntary U.S. pension plan contributions | 159 | 83 |
| U.S. domestic pension contributions | 165 | $ 165 |
| September 2015 U.S. Pension Plans contribution | $ 165 | |