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Retirement Plans - Actuarial Assumptions Used for Pension Plans & Postretirement Medical Plan (Detail)
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Pension Plans      
Benefit Obligations:      
Discount rate 4.80% 5.00% 2.50%
Rate of compensation increase 3.90% 4.00% 3.80%
Net Periodic Benefit Cost:      
Expected rate of return on plan assets 6.50% 6.50% 6.60%
Rate of compensation increase 4.00% 3.80% 3.80%
Pension Plans | Service Cost      
Net Periodic Benefit Cost:      
Discount rate, Service cost 5.00% 3.30% 2.60%
Pension Plans | Interest Cost      
Net Periodic Benefit Cost:      
Discount rate, Service cost 4.90% 3.00% 1.70%
Postretirement Medical Plan      
Benefit Obligations:      
Discount rate 4.70% 4.90% 2.40%
Initial health care trend rate 6.00% 6.30% 5.50%
Ultimate trend rate 4.00% 4.00% 4.00%
Year in which ultimate trend rate is reached 2046 2046 2046