Pension and Other Postretirement Benefits - Benefit Obligations in Excess of Plan Assets (Detail) - USD ($) $ in Millions |
Sep. 30, 2019 |
Sep. 30, 2018 |
|---|---|---|
| U.S. Plans | ||
| Accumulated benefit obligation in excess of plan assets | ||
| Accumulated benefit obligation—end of year | $ (7) | $ (6) |
| Fair value of plan assets—end of year | 0 | 0 |
| Projected benefit obligation in excess of plan assets | ||
| Benefit obligation—end of year | (7) | (6) |
| Fair value of plan assets—end of year | 0 | 0 |
| Non-U.S. Plans | ||
| Accumulated benefit obligation in excess of plan assets | ||
| Accumulated benefit obligation—end of year | (528) | (452) |
| Fair value of plan assets—end of year | 490 | 436 |
| Projected benefit obligation in excess of plan assets | ||
| Benefit obligation—end of year | (528) | (452) |
| Fair value of plan assets—end of year | $ 490 | $ 436 |