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Retirement Plans, Weighted-Average Assumption Used to Determine Benefit Obligation (Details) | 12 Months Ended
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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.

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- Definition Defined Benefit Plan, Initial Health Care Cost Trend Rate + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Ultimate trend rate for health care cost for defined benefit postretirement plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Year ultimate health care cost trend rate is expected to be reached, in YYYY format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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