For the three and six months ended April 30, 2017 and 2016, our net pension and post-retirement benefit cost (benefit) were comprised of the following: | | | | | | | | | | | | | | | | | | | | | | | | | | Pensions | | | | U.S. Defined Benefit Plans | | Non-U.S. Defined Benefit Plans | | U.S. Post-Retirement Benefit Plan | | Three Months Ended April 30, | | 2017 | | 2016 | | 2017 | | 2016 | | 2017 | | 2016 | | (in millions) | Service cost—benefits earned during the period | $ | 6 |
| | $ | 5 |
| | $ | 4 |
| | $ | 4 |
| | $ | — |
| | $ | — |
| Interest cost on benefit obligation | 5 |
| | 6 |
| | 5 |
| | 8 |
| | 2 |
| | 2 |
| Expected return on plan assets | (9 | ) | | (9 | ) | | (18 | ) | | (18 | ) | | (3 | ) | | (4 | ) | Amortization: | | | | | | | | | | | | Net actuarial losses | 3 |
| | 2 |
| | 8 |
| | 7 |
| | 6 |
| | 5 |
| Prior service credit | (1 | ) | | (2 | ) | | (1 | ) | | — |
| | (4 | ) | | (4 | ) | Total periodic benefit cost (benefit) | $ | 4 |
| | $ | 2 |
| | $ | (2 | ) | | $ | 1 |
| | $ | 1 |
| | $ | (1 | ) |
| | | | | | | | | | | | | | | | | | | | | | | | | | Pensions | | | | U.S. Defined Benefit Plans | | Non-U.S. Defined Benefit Plans | | U.S. Post-Retirement Benefit Plan | | Six Months Ended April 30, | | 2017 | | 2016 | | 2017 | | 2016 | | 2017 | | 2016 | | (in millions) | Service cost—benefits earned during the period | $ | 11 |
| | $ | 10 |
| | $ | 8 |
| | $ | 8 |
| | $ | — |
| | $ | — |
| Interest cost on benefit obligation | 10 |
| | 12 |
| | 11 |
| | 16 |
| | 4 |
| | 4 |
| Expected return on plan assets | (17 | ) | | (18 | ) | | (37 | ) | | (37 | ) | | (6 | ) | | (7 | ) | Amortization: | | | | | | | | | | | | Net actuarial losses | 7 |
| | 4 |
| | 17 |
| | 14 |
| | 11 |
| | 10 |
| Prior service credit | (3 | ) | | (4 | ) | | (1 | ) | | — |
| | (8 | ) | | (8 | ) | Settlement gain | — |
| | — |
| | (68 | ) | | — |
| | — |
| | — |
| Total periodic benefit cost (benefit) | $ | 8 |
| | $ | 4 |
| | $ | (70 | ) | | $ | 1 |
| | $ | 1 |
| | $ | (1 | ) |
|