Accumulated Other Comprehensive Income (Loss) ("AOCI") - Additional Information (Detail) - U K Termination Plans [Member] $ in Millions |
9 Months Ended |
|---|---|
|
Jun. 30, 2026
USD ($)
| |
| Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | |
| Settlement gain loss on pension plan termination | $ (29) |
| Defined benefit plan settlement charge recognized amount | $ 1 |