Postretirement Benefit Plans - Employer Contributions to Plans (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Contributions to employee benefit plans | ||
| Funded pension plans | $ 12 | $ 13 |
| Unfunded pension plans | 4 | 4 |
| Savings and defined contribution pension plans | 18 | 18 |
| Total contributions | $ 34 | $ 35 |