v3.26.1
Schedule of Assets (Held at End of Year) (Details) - EBP 004
12 Months Ended
Dec. 31, 2025
USD ($)
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Plan Number 004
Entity Tax Identification Number 74-1884980
EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution $ 28,882,175 [1]
EBP, Asset Held for Investment, Total $ 944,707,449
EBP, Asset Held for Investment, Participant Loan, Maturity Date Mar. 15, 2039 [1]
Investment, Identifier [Axis]: Common Trust Funds  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 582,080,966
Investment, Identifier [Axis]: Common Trust Funds BlackRock Russell 2000 Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] BlackRock [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 40,256,378
Investment, Identifier [Axis]: Common Trust Funds Franklin Templeton Putnam Large Cap Value Trust CL1  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Franklin Templeton [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 38,099,106
Investment, Identifier [Axis]: Common Trust Funds Invesco Stable Value Retirement Fund CL1  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Invesco [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 97,253,884
Investment, Identifier [Axis]: Common Trust Funds Northern Trust Aggregate Bond Index DC NL Tier 3  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Northern Trust [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 65,602,299
Investment, Identifier [Axis]: Common Trust Funds Northern Trust MSCI ACWI EX US Index TR 3  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Northern Trust [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 79,543,793
Investment, Identifier [Axis]: Common Trust Funds Northern Trust S&P 500 Tier 3  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Northern Trust [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 175,687,980
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2010A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 1,498,140
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2015A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 1,770,041
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2020A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 14,024,832
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2025A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 8,296,900
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2030A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 19,522,473
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2035A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 10,656,944
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2040A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 16,769,470
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2045A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 5,466,494
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2050A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 4,184,855
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2055A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 2,756,961
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2060A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 409,439
Investment, Identifier [Axis]: Common Trust Funds T. Rowe Price retirement 2065A TR  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] T. Rowe Price [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 280,977
Investment, Identifier [Axis]: Common stock Kirby Corporation Common stock  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Kirby Corporation Common stock [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] EBP, Employer, Common Stock [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Party-in-Interest [true false] true
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 53,677,515 [1]
Investment, Identifier [Axis]: Mutual Funds  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 280,066,793
Investment, Identifier [Axis]: Mutual Funds American Century Small Cap GR R6  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] American Century [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 21,645,481
Investment, Identifier [Axis]: Mutual Funds American Funds American Bond Fund of America Class R-6  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] American Funds [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 20,175,898
Investment, Identifier [Axis]: Mutual Funds Blackrock Global Allocation Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] BlackRock [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 3,951,024
Investment, Identifier [Axis]: Mutual Funds Dimensional Fund Advisors DFA Real Estate Securities Portfolio Institutional Class  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Dimensional Fund Advisors [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 12,999,376
Investment, Identifier [Axis]: Mutual Funds Fidelity Mid Cap Index  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Fidelity [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 42,611,039
Investment, Identifier [Axis]: Mutual Funds Harbor International Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Harbor [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 51,132,452
Investment, Identifier [Axis]: Mutual Funds Northern Trust Active Multi-Manager Emerging Markets Equity Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Northern Trust [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 10,904,155
Investment, Identifier [Axis]: Mutual Funds PIMCO Rae US Small Fund Institutional Class  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] PIMCO [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 23,518,042
Investment, Identifier [Axis]: Mutual Funds Prudential Jennison Large Cap Growth Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Investment, Issuer Name [Extensible Enumeration] Prudential Jennison [Member]
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value $ 93,129,326
Minimum  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Asset Held for Investment, Participant Loan, Interest Rate 4.00% [1]
EBP, Asset Held for Investment, Participant Loan, Maturity Date Jan. 07, 2026
Maximum  
EBP, Schedule of Asset Held for Investment [Line Items]  
EBP, Asset Held for Investment, Participant Loan, Interest Rate 10.30% [1]
EBP, Asset Held for Investment, Participant Loan, Maturity Date Mar. 15, 2039
[1] Parties in interest to the Plan