Pension and Other Postretirement Benefits - Weighted Average Actuarial Assumptions (Detail) |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
| U.S. Plans | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Discount rate for benefit obligation | 3.26% | 4.23% | 3.84% |
| Discount rate for net periodic benefit cost | 4.23% | 3.84% | 3.62% |
| Expected long-term rate of return on plan assets | 7.00% | 7.00% | 7.00% |
| Non-U.S. Plans | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Discount rate for benefit obligation | 1.80% | 2.90% | 2.70% |
| Discount rate for net periodic benefit cost | 2.90% | 2.70% | 2.40% |
| Expected long-term rate of return on plan assets | 3.00% | 4.25% | 4.50% |
| Rate of increase in compensation levels for: | |||
| Benefit obligation | 2.50% | 3.20% | 3.20% |
| Net periodic benefit cost | 2.50% | 3.20% | 3.20% |