v3.26.1
Postretirement Benefit Plans (Actuarial Assumptions and Sensitivity Analysis) (Details)
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine net periodic benefit cost, Expected return on plan assets 6.30%    
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine benefit obligations, Discount rate 4.60% 4.50% 4.40%
Weighted average assumptions used to determine benefit obligations, Average compensation growth 2.90% 3.00% 3.00%
Weighted average assumptions used to determine net periodic benefit cost, Discount rate 4.50% 4.40% 4.50%
Weighted average assumptions used to determine net periodic benefit cost, Average compensation growth 3.00% 3.00% 3.10%
Weighted average assumptions used to determine net periodic benefit cost, Expected return on plan assets 6.50% 6.30% 6.10%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate 1.40% 1.60% 2.20%
Other Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine benefit obligations, Discount rate 6.00% 5.80% 5.70%
Weighted average assumptions used to determine benefit obligations, Average compensation growth 3.00% 3.00% 3.00%
Weighted average assumptions used to determine net periodic benefit cost, Discount rate 5.80% 5.70% 5.50%
Weighted average assumptions used to determine net periodic benefit cost, Average compensation growth 3.00% 3.00% 3.00%
Weighted average assumptions used to determine net periodic benefit cost, Expected return on plan assets 0.00% 0.00% 0.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate 0.00% 0.00% 0.00%