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Retirement Plans, Information About Plan Assets and Asset Allocation (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Information about Plan Assets [Abstract] |  |  |  |  |
Service period of participants not impacted by pension plan amendment |  | 15 years |  |  |
Age of plan participants not impacted by pension plan amendment |  | 50 years |  |  |
Service period of participants who are age fifty not impacted by pension plan amendment |  | 10 years |  |  |
Real Estate Investment [Member] | Level 3 [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Fair value of plan assets |  | $ 0 | $ 138,000,000 |  |
Cash and Equity Securities [Member] | Level 1 [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Fair value of plan assets |  | 5,406,000 | 25,032,000 |  |
Plan 2018 [Member] | Higman [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  |  |  | $ 1,615,000 |
Plan 2019 [Member] | Higman [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  | 479,000 | 797,000 | 1,449,000 |
Plan 2020 [Member] | Higman [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  |  | 1,438,000 |  |
Pension Plan [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  | 479,000 | 2,235,000 |  |
Fair value of plan assets |  | $ 430,821,000 | $ 395,137,000 | $ 358,197,000 |
Expected long-term rate of return on plan assets |  | 6.75% | 6.75% | 7.00% |
Contribution percentage to defined contribution plan |  | 92.00% |  |  |
Discount rate |  | 2.80% | 3.50% | 4.40% | [1]
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Asset allocations |  | 100.00% | 100.00% |  |
Pension Plan [Member] | Minimum [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Discount rate |  | 2.80% | 3.10% |  |
Pension Plan [Member] | Maximum [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Discount rate |  | 2.90% | 3.50% |  |
Pension Plan [Member] | Higman [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Discount rate |  | 2.90% | 3.10% |  |
Pension Plan [Member] | U.S. Equity Securities [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Asset allocations |  | 51.00% | 53.00% |  |
Target allocations |  | 50.00% |  |  |
Pension Plan [Member] | U.S. Equity Securities [Member] | Minimum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 30.00% |  |  |
Pension Plan [Member] | U.S. Equity Securities [Member] | Maximum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 70.00% |  |  |
Pension Plan [Member] | International Equity Securities [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Asset allocations |  | 20.00% | 20.00% |  |
Target allocations |  | 20.00% |  |  |
Pension Plan [Member] | International Equity Securities [Member] | Minimum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 0.00% |  |  |
Pension Plan [Member] | International Equity Securities [Member] | Maximum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 30.00% |  |  |
Pension Plan [Member] | Debt Securities [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Asset allocations |  | 29.00% | 25.00% |  |
Target allocations |  | 30.00% |  |  |
Pension Plan [Member] | Debt Securities [Member] | Minimum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 15.00% |  |  |
Pension Plan [Member] | Debt Securities [Member] | Maximum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 55.00% |  |  |
Pension Plan [Member] | Cash and Cash Equivalents [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Asset allocations |  | 0.00% | 2.00% |  |
Target allocations |  | 0.00% |  |  |
Pension Plan [Member] | Cash and Cash Equivalents [Member] | Minimum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 0.00% |  |  |
Pension Plan [Member] | Cash and Cash Equivalents [Member] | Maximum [Member] |  |  |  |  |
Asset Allocation Among Asset Categories [Abstract] |  |  |  |  |
Target allocations |  | 5.00% |  |  |
SERP [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  | $ 160,000 | $ 146,000 |  |
Fair value of plan assets |  | $ 0 | $ 0 | $ 0 |
Expected long-term rate of return on plan assets |  | 0.00% | 0.00% | 0.00% |
Discount rate | [1] | 2.80% | 3.50% | 4.40% |
Other Postretirement Benefits [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  | $ 168,000 | $ 139,000 |  |
Fair value of plan assets |  | $ 0 | $ 0 | $ 0 |
Pension plan defined benefit plan cost increase limit percentage |  | 4.00% |  |  |
Discount rate |  | 2.80% | 3.50% | 4.40% |
Seafarers Pension Trust [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  | $ 541,000 | $ 617,000 |  |
Contribution percentage to defined contribution plan |  |  | 100.00% |  |
Central Pension Fund of the International Union of Operating [Member] |  |  |  |  |
Information about Plan Assets [Abstract] |  |  |  |  |
Pension contributions |  | $ 693,000 | $ 691,000 |  |
Contribution percentage to defined contribution plan |  |  | 98.00% |  |
[1] | The 2021 discount rate for benefit cost is 2.8% for the Kirby Pension Plan and 2.9% for the Higman Pension Plan. The 2020 discount rate for benefit cost is 3.5% 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 -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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