Benefit Plans - Narrative (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Retirement Benefits [Abstract] | |||
| Pension Plans' expense | $ 3 | $ 4 | $ 5 |
| Company's contribution to the Savings Plans | 11 | 9 | 9 |
| Expense included in general and administrative expenses for postretirement plans | $ 2 | $ 3 | $ 3 |