v3.26.1
RETIREMENT-RELATED BENEFITS - Assumptions (Details) - Pension Plans
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Weighted-average assumptions used to measure net periodic benefit cost      
Discount rate 3.68% 3.30% 3.57%
Expected long-term returns on plan assets 4.77% 4.63% 4.69%
Rate of compensation increase 2.80% 2.84% 2.85%
Weighted-average assumptions used to measure benefit obligations      
Discount rate 4.31% 3.68% 3.30%
Rate of compensation increase 2.95% 2.80% 2.84%
Interest crediting rate - cash balance plans 1.90% 1.83% 1.65%