Employee Benefit Plans - Healthcare Cost Trend Rates (Details) - Officer Medical Plan - Other Postretirement Benefits Plan |
12 Months Ended | |
|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Defined Benefit Plan Disclosure [Line Items] | ||
| Health care cost trend rate assumed for next year, Pre 65 | 8.25% | 7.25% |
| Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), Pre 65 | 4.50% | 4.50% |
| Health care cost trend rate assumed for next year, Post 65 | 8.95% | 7.50% |
| Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), Post 65 | 4.50% | 4.50% |