XML 86 R71.htm IDEA: XBRL DOCUMENT v3.22.0.1
Retirement Plans, Weighted-Average Assumption Used to Determine Benefit Obligation (Details)
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Pension Plan [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate 3.00% 2.80%
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] 3.00% 2.80%
Pension Plan [Member] | Maximum [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate [1] 3.10% 2.90%
Pension Plan [Member] | Higman [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate 3.10% 2.90%
SERP [Member]    
Weighted-average assumption used to determine benefit obligation at end of year [Abstract]    
Discount rate [1] 3.00% 2.80%
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] 3.00% 2.80%
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 2027 2025
[1] The 2021 discount rate was 3.0% for the Kirby Pension Plan and 3.1% for the Higman Pension Plan. The 2020 discount rate was 2.8% for the Kirby Pension Plan and 2.9% for the Higman Pension Plan.