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Retirement Plans, Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost, Pension Benefits (Details) | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Pension Benefits [Member] |  |  |  |  |  |
Weighted average assumptions used to determine net periodic benefit cost [Abstract] |  |  |  |  |  |
Discount rate |  | 5.50% | [1] | 3.00% |  |
Expected long-term rate of return on plan assets |  | 6.75% |  | 6.75% |  | 6.75%
Pension Benefits [Member] | Maximum [Member] |  |  |  |  |  |
Weighted average assumptions used to determine net periodic benefit cost [Abstract] |  |  |  |  |  |
Discount rate |  |  |  | 3.10% | [1] | 2.90%
Pension Benefits [Member] | Minimum [Member] |  |  |  |  |  |
Weighted average assumptions used to determine net periodic benefit cost [Abstract] |  |  |  |  |  |
Discount rate |  |  |  | 3.00% | [1] | 2.80%
SERP [Member] |  |  |  |  |  |
Weighted average assumptions used to determine net periodic benefit cost [Abstract] |  |  |  |  |  |
Discount rate | [1] | 5.50% |  | 3.00% |  | 2.80%
Expected long-term rate of return on plan assets |  | 0.00% |  | 0.00% |  | 0.00%
Rate of compensation increase |  | 0.00% |  | 0.00% |  | 0.00%
Higman Pension Plan [Member] |  |  |  |  |  |
Weighted average assumptions used to determine net periodic benefit cost [Abstract] |  |  |  |  |  |
Discount rate |  |  |  | 3.10% |  |
[1] | The 2023 discount rate for benefit cost is 5.5% for both the Kirby Pension Plan and the Higman Pension Plan. The 2022 discount rate for benefit cost is 3.0% for the Kirby Pension Plan and 3.1% for the Higman Pension Plan.

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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost 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 of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost 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 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate of compensation increase used to determine net periodic benefit cost 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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- References No definition available. + Details
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