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Retirement Plans, Weighted-Average Assumption Used to Determine Benefit Obligation (Details)
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Pension Plan [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate 5.10% 5.50% [1]
Health care cost trend rate [Abstract]    
Initial rate 0.00% 0.00%
Ultimate rate 0.00% 0.00%
Pension Plan [Member] | Minimum [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate [1] 5.10%  
Pension Plan [Member] | Maximum [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate [1] 5.20%  
SERP [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate [1] 5.10% 5.50%
Rate of compensation increase 0.00% 0.00%
Health care cost trend rate [Abstract]    
Initial rate 0.00% 0.00%
Ultimate rate 0.00% 0.00%
Other Postretirement Benefits [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate [1] 5.10% 5.50%
Rate of compensation increase 0.00% 0.00%
Health care cost trend rate [Abstract]    
Initial rate 6.25% 6.50%
Ultimate rate 5.00% 5.00%
Years to ultimate 2029 2029
Higman Pension Plan [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate 5.20% 5.50%
[1] The 2023 discount rate was 5.1% for the Kirby Pension Plan and 5.2% for the Higman Pension Plan. The 2022 discount rate was 5.5% for both the Kirby Pension Plan and the Higman Pension Plan.