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RETIREMENT BENEFITS PLANS - Other Postretirement Benefits Plan Assumptions (Details) - Other postretirement benefits expense (income)
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Assumptions used to determine benefit obligation at year-end (as a percent)      
Discount rate 5.24% 5.57% 5.11%
Health care cost trend rate assumed for next year 6.50% 6.70% 7.70%
Ultimate health care cost trend rate 4.75% 4.75% 4.75%
Year ultimate health care cost trend rate is achieved 2035 2034 2033
Assumptions used to determine expense (as a percent)      
Discount rate used to determine benefit obligation 5.57% 5.11% 5.46%
Discount rate used to determine service cost 5.84% 5.25% 5.53%
Discount rate used to determine interest cost 5.29% 4.96% 5.32%
Initial health care cost trend rate 6.70% 7.70% 7.10%
Ultimate health care cost trend rate 4.75% 4.75% 4.75%
Year ultimate health care cost trend rate is achieved 2034 2033 2031