XML 293 R88.htm IDEA: XBRL DOCUMENT v3.24.1.1.u2
Employee Benefit Plans - Healthcare Cost Trend Rates (Details) - Officer Medical Plan - Other Postretirement Benefits Plan
 12 Months Ended
Mar. 31, 2024
Mar. 31, 2023
Defined Benefit Plan Disclosure [Line Items]    
Health care cost trend rate assumed for next year, Pre 65 7.25% 6.60%
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 7.50% 6.80%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate), Post 65 4.50% 4.50%