v3.26.1
Postretirement Benefit Plans (Employer Contributions to Plans) (Details) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Contributions to employee benefit plans      
Funded pension plans $ 29 $ 39 $ 30
Unfunded pension plans 17 17 17
Savings and defined contribution pension plans 63 62 59
Total contributions 109 118 106
Defined Benefit Plan Disclosure [Line Items]      
Payment for Pension and Other Postretirement Benefits 109 $ 118 $ 106
Additional Contributions To Funded Pension Plan 34    
Additional Contributions To Unfunded Pension Plan 19    
Employer discretionary contribution amount $ 64