Cover [Abstract] Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Three Amendment Description Amendment Flag City Area Code Entity Address, City or Town Entity Address, Country Current Fiscal Year End Date Document Period End Date Entity Incorporation, State or Country Code Local Phone Number Entity Address, Postal Zip Code Entity Address, State or Province Title of 12(b) Security No Trading Symbol Flag Trading Symbol Security Exchange Name Entity Current Reporting Status Entity Filer Category Entity Registrant Name Entity Central Index Key Entity Tax Identification Number Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Document Type Document Quarterly Report Document Transition Report Entity Interactive Data Current Entity File Number Entity Shell Company Entity Emerging Growth Company Entity Small Business Award Type [Axis] ASU 2018-02 [Member] Accounting Standards Update 2018-02 [Member] Accounts payable Accounts Payable, Current Trade - less allowance for doubtful accounts Accounts Receivable, after Allowance for Credit Loss, Current Accounts receivable: Accounts Receivable, after Allowance for Credit Loss, Current [Abstract] Receivable Accounts Receivable, after Allowance for Credit Loss Accrued liabilities Accrued Liabilities, Current Income taxes payable Accrued Income Taxes, Current Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Accumulated other comprehensive income - net Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive, Net Income [Member] AOCI Attributable to Parent [Member] Weighted average amortization period of intangibles Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Additional paid-in capital Adjustments to reconcile net earnings (loss) to net cash provided by operations: Tax withholdings on equity award vesting Share-based Payment Arrangement, Decrease for Tax Withholding Obligation Adjustments for New Accounting Pronouncements [Axis] Other [Member] Other Segments [Member] Compensation cost Share-based Payment Arrangement, Expense Antidilutive securities excluded from computation of earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Impairments and Other Charges [Abstract] Impairments and Other Charges Impairments and other charges Asset Impairment Charges ASSETS Assets [Abstract] Total assets Total assets Assets Total current assets Assets, Current Current assets: Basis for Preparation of the Condensed Financial Statements Basis of Accounting [Text Block] Liabilities [Abstract] Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract] Accounts payable and accrued liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable Prepaid expenses Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Assets [Abstract] Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract] Other long-term liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other Other intangibles Total assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Total liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Business Acquisition [Line Items] Business Acquisition [Axis] Acquisitions [Abstract] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Acquisitions [Abstract] Business Combination, Separately recognized Transactions, Additional Disclosures [Abstract] Inventories Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Property and equipment Acquisitions Business Combination Disclosure [Text Block] Fair values of assets acquired and liabilities assumed, net [Abstract] Net assets acquired Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Cash and cash equivalents, beginning of year Cash and cash equivalents, end of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents Increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Contingencies and commitments Commitments and Contingencies Contingencies [Abstract] Contingencies Commitments and Contingencies Disclosure [Text Block] Common Stock [Member] Common Stock [Member] Common stock, par value per share (in dollars per share) Common stock, shares issued (in shares) Common stock, shares authorized (in shares) Common stock, $0.10 par value per share. Authorized 120,000,000 shares, issued 65,472,000 shares Common Stock, Value, Issued Retirement Plans [Abstract] Comprehensive income (loss) attributable to Kirby Comprehensive income (loss) attributable to Kirby Comprehensive Income (Loss), Net of Tax, Attributable to Parent Total comprehensive income (loss), net of taxes Total comprehensive income (loss), net of taxes Total comprehensive income (loss), net of taxes Revenue recognized Deferred revenues Contract assets Total costs and expenses Total costs and expenses Costs and Expenses Costs and expenses: Costs and Expenses [Abstract] Credit Facility [Domain] Credit Facility [Axis] Current Current State and Local Tax Expense (Benefit) Foreign - current State and local [Abstract] Current Current Federal Tax Expense (Benefit) Customer Relationships [Member] Customer Relationships [Member] Revenues by Major Source Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Table] Disaggregation of Revenue [Abstract] Long-Term Debt [Abstract] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Senior Notes outstanding Debt Instrument [Line Items] Debt Instrument, Name [Domain] Interest rate Debt Instrument, Interest Rate, Stated Percentage Estimated fair value of outstanding debt Maturity Date Debt Instrument, Maturity Date Debt instrument, frequency of periodic payment Performance Bonds [Member] Debt Securities Payable [Member] Long-term Debt [Abstract] Debt Instruments [Abstract] Deferred income taxes Deferred Income Tax Liabilities, Net Deferred Deferred Federal Income Tax Expense (Benefit) Provision (benefit) for deferred income taxes Provision (Bbenefit) for deferred income taxes Deferred Retirement Plans [Abstract] Defined Benefit Plan, Additional Information [Abstract] Expected pension contributions Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Amortization of actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Defined Benefit Plan Disclosure [Line Items] Pension contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Components of net periodic benefit cost [Abstract] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Interest cost Defined Benefit Plan, Interest Cost Service cost Defined Benefit Plan, Service Cost Depreciation and amortization Stock Award Plans [Abstract] Stock Award Plans Share-based Payment Arrangement [Text Block] Distributorships [Member] Distribution Rights [Member] United States [Member] Domestic Tax Authority [Member] Net earnings (loss) per share attributable to Kirby common stockholders: Net earnings (loss) per share attributable to Kirby common stockholders: Earnings Per Share Earnings Per Share [Text Block] Loss per common share - basic and diluted (in dollars per share) Earnings Per Share, Basic and Diluted Diluted (in dollars per share) Diluted (in dollars per share) Basic (in dollars per share) Basic (in dollars per share) Earnings Per Share [Abstract] Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] Effective income tax rate Income tax benefit Share-based Payment Arrangement, Expense, Tax Benefit Stock Options [Member] Equity Component [Domain] Equity Component [Domain] Error Corrections and Prior Period Adjustments Restatement [Line Items] Fair Value, Inputs, Level 1, 2 and 3 [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Axis] Level 2 [Member] Federal [Abstract] Federal Income Tax Expense (Benefit), Continuing Operations [Abstract] Fair Value Measurements [Abstract] Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Other intangibles - net Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets by Major Class [Axis] Intangible assets amortization period Finite-Lived Intangible Asset, Useful Life Foreign [Member] Foreign Tax Authority [Member] Gain on disposition of assets Gain on disposition of assets Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Impairment Goodwill, Impairment Loss Convoy acquisition Balance (gross) Balance (gross) Goodwill, Gross Goodwill Balance Balance Goodwill Changes in Goodwill [Roll Forward] Accumulated impairment and amortization Accumulated impairment and amortization Goodwill, Impaired, Accumulated Impairment Loss Goodwill [Line Items] Guarantor Obligations [Line Items] Guarantor Obligations, Nature [Axis] Issued guaranties Guarantor Obligations, Maximum Exposure, Undiscounted Guarantor Obligations, Nature [Domain] Guaranties [Abstract] Guarantees [Abstract] Intersegment Eliminations [Member] Non-cash write-down Impairment charge Income Approach [Member] Income Tax Authority [Axis] Taxes on Income [Abstract] Earnings (loss) before taxes on income Segment profit (loss) Earnings (loss) before taxes on income Earnings (Loss loss) before taxes on income CONDENSED STATEMENTS OF EARNINGS (Unaudited) [Abstract] Condensed Statement of Earnings [Abstract] Earnings (loss) before taxes on income [Abstract] Taxes on Income (Provision) benefit for taxes on income Total Provision for taxes on income (Provision) Benefit benefit for taxes on income Income Tax Expense (Benefit) Income Tax Authority [Domain] Income taxes refunded Income Taxes Paid, Net Decrease in deferred tax asset Increase (Decrease) in Deferred Income Taxes Decrease in cash flows resulting from changes in operating assets and liabilities, net Increase (Decrease) in Operating Capital Increase (Decrease) in Stockholders' Equity [Roll Forward] Dilutive effect of stock options and restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Interest expense Interest Expense Interest paid Finished goods Inventories [Abstract] Inventories Inventory Disclosure [Text Block] Inventories - net Inventories - net Inventory, Net Work in process Details of inventories [Abstract] Inventory, Net [Abstract] Investment in affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Leases Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five 2021/2020 Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months 2024/2023 Lessee, Operating Lease, Liability, Payments, Due Year Four 2024 Lessee, Operating Lease, Liability, Payments, Due Year Five Total lease payments Lessee, Operating Lease, Liability, Payments, Due Future Minimum Lease Payments under Operating Leases 2020 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year Less: imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount 2023/2022 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022/2021 Lessee, Operating Lease, Liability, Payments, Due Year Two Lease Cost [Abstract] Total lease cost Lease, Cost Lease Cost Leases [Abstract] Letter of Credit [Member] LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] Total liabilities and equity Total liabilities and equity Liabilities and Equity Total long-term liabilities Total long-term liabilities Liabilities, Noncurrent Current liabilities: Total current liabilities Liabilities, Current Credit facility, amount outstanding Credit facility, expiration date Line of Credit Facility, Expiration Date Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Term loan Long-term Debt Long-Term Debt Long-term Debt [Text Block] Long-term debt, net - less current portion Long-term Debt, Excluding Current Maturities Loss Contingency [Abstract] Loss Contingencies [Line Items] Loss Contingency Nature [Axis] Loss Contingencies [Table] Loss Contingency, Nature [Domain] Return of investment to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Noncontrolling interests COVID-19 [Member] Net Income (Loss) Attributable to Parent [Abstract] Net Income (Loss) Attributable to Parent [Abstract] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Cash flows from operating activities: Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Net earnings (loss) attributable to Kirby Net earnings (loss) attributable to Kirby Net earnings (loss) attributable to Kirby Net Income (Loss) Attributable to Parent Income (loss) available to Kirby common stockholders - basic Net Income (Loss) Available to Common Stockholders, Basic Cash flows from financing activities: Income (loss) available to Kirby common stockholders - diluted Net Income (Loss) Available to Common Stockholders, Diluted Less: Net earnings attributable to noncontrolling interests Net earnings attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Accounting Standards Adoptions New Accounting Pronouncements, Policy [Policy Text Block] Accounting Standards Adoptions [Abstract] Accounting Standards Adoptions New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Non-compete Agreements [Member] Other income (expense) Other income (expense) Bank notes payable Number of reportable segments Number of Reportable Segments Noncontrolling Interests [Member] Noncontrolling Interest [Member] Oil and Gas [Member] Operating losses tax year Open Tax Year Future Minimum Lease Payments Under Operating Leases [Abstract] Weighted average remaining lease term Operating lease right-of-use assets Operating lease cost Operating Lease, Cost Reporting Segments [Member] Operating Segments [Member] Weighted average discount rate Operating income (loss) Operating income (loss) Operating Income (Loss) Current portion of operating lease liabilities Operating lease liabilities - less current portion Operating cash outflow from operating leases Operating lease liabilities Operating Lease, Liability Basis for Preparation of the Condensed Financial Statements [Abstract] Amortization of net actuarial loss, Net Amount Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Amortization of net actuarial loss, Income Tax Provision Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax Amortization of net actuarial loss, Gross Amount Foreign currency translation, Income Tax Provision Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Foreign currency translation adjustments Foreign currency translation, Net Amount Pension and postretirement benefits Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Total other comprehensive income, Gross Amount Other Comprehensive Income (Loss), before Tax Foreign currency translation, Gross Amount Total other comprehensive income (loss), net of taxes Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income Other Comprehensive Income, Noncontrolling Interest [Text Block] Other Other Noncash Income (Expense) Details of "Other" total assets [Abstract] Total other assets Other Assets Total other comprehensive income, Income Tax Provision Other Comprehensive Income (Loss), Tax Pension and postretirement benefits [Abstract] Other comprehensive income (loss), net of taxes: Other assets Other Assets, Noncurrent Impairments and other charges Other Asset Impairment Charges Other Comprehensive Income [Abstract] Other long-term liabilities Other Postretirement Benefits [Member] Other Postretirement Benefits [Member] Other Other Receivables Payments related to tax withholding for share-based compensation Payment, Tax Withholding, Share-based Payment Arrangement Acquisitions of businesses and marine equipment Payments to Acquire Businesses, Net of Cash Acquired Payments of debt issue costs Payments of Debt Issuance Costs Cash paid for acquisition Cash paid for acquisition Payments to Acquire Businesses, Gross Capital expenditures Purchase price Payments to Acquire Productive Assets Pension Plan [Member] Pension Plan [Member] Retirement Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Prepaid expenses and other current assets Other Borrowings (payments) on bank credit facilities, net Proceeds from (Repayments of) Lines of Credit Borrowings on long-term debt Proceeds from disposition of assets Proceeds from exercise of stock options Net earnings (loss) Net earnings (loss) Net earnings (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Property and equipment Property, Plant and Equipment, Gross Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property and equipment - net Property, Plant and Equipment, Net Right-of-use assets obtained in exchange for lease obligations Payments on long-term debt Payments on long-term debt Repayments of Long-term Debt Restricted Stock [Member] RSUs [Member] Retained Earnings [Member] Retained Earnings [Member] Retained earnings Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Revenue, Performance Obligation [Abstract] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenues [Abstract] Expected timing of satisfaction, period Revenues Revenue from Contract with Customer [Text Block] Total revenues Revenues Revenues by major source Revenues: Revolving Credit Facility [Member] Sublease income Sublease Income Stock options expiration period Details of Inventories Fair Values of Assets Acquired and Liabilities Assumed Earnings Before Taxes Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Compensation Cost Breakdown in Statement of Earnings Basic and Diluted Earnings per Share Changes in Other Comprehensive Income Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] Effects of Restatement Resulting from Error Correction Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] Net Periodic Benefit Cost Schedule of Defined Benefit Plans Disclosures [Table Text Block] Changes in Goodwill Schedule of Goodwill [Table] Schedule of Guarantor Obligations [Table] Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Segment Data Segment Reporting Disclosure [Text Block] Segment Reporting Information [Line Items] Segments [Domain] Segment Data [Abstract] Revenues [Abstract] Segment Reporting Information, Revenue for Reportable Segment [Abstract] Selling, general and administrative Amortization of unearned share-based compensation Share-based Payment Arrangement, Noncash Expense Number of stock options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] Number of restricted stock and units granted (in shares) Equity Award [Domain] Tax withholdings on equity award vesting (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding Short-term lease cost Letters of Credit [Member] Standby Letters of Credit [Member] CONDENSED BALANCE SHEETS (Unaudited) [Abstract] Condensed Balance Sheet [Abstract] CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract] Condensed Statement of Comprehensive Income [Abstract] Equity Components [Axis] Statement [Line Items] Statement [Table] Segments [Axis] CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) [Abstract] Condensed Statement of Cash Flows [Abstract] CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) [Abstract] Condensed Statement of Stockholders' Equity [Abstract] Stock option exercises (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Issuance of stock for equity awards, net of forfeitures (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Stock option exercises Stock Issued During Period, Value, Stock Options Exercised Issuance of stock for equity awards, net of forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Equity: Total Kirby stockholders' equity Total Kirby stockholders' equity Stockholders' Equity Attributable to Parent Beginning balance Ending balance Total equity Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Kirby stockholders' equity: Subsequent Event [Table] Subsequent Events Subsequent Events [Member] Subsequent Event Type [Domain] Subsequent Event [Line Items] Subsequent Events [Abstract] Subsequent Event Type [Axis] Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] SERP [Member] Supplemental Employee Retirement Plan [Member] Taxes, other than on income Taxes, Miscellaneous Treasury stock, shares (in shares) Treasury stock - at cost, 5,475,000 shares at March 31, 2020 and 5,513,000 at December 31, 2019 Treasury Stock, Value Treasury Stock [Member] Treasury Stock [Member] Type of Adoption [Domain] Underlying Asset Class [Domain] Underlying Asset Class [Axis] Collision with M/S Summer Wind [Member] Undistributed earnings allocated to restricted shares Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Undistributed earnings allocated to restricted shares Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted Unusual or Infrequent Item, or Both [Domain] Unusual or Infrequent Item, or Both [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] Variable lease cost Weighted average unvested restricted stock (in shares) Weighted Average Number of Shares, Restricted Stock Weighted average common stock outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted average common stock outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Consolidation Items [Domain] Consolidation Items [Axis] Maximum [Member] Maximum [Member] Products and Services [Domain] Products and Services [Axis] Statistical Measurement [Domain] Statistical Measurement [Axis] Restatement [Domain] Adjustment [Member] Restatement Adjustment [Member] Restatement [Axis] Previously Reported [Member] Marine transportation - A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. Marine Transportation [Member] Marine Transportation [Member] Costs incurred and are directly related to generating revenues and generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services, excludes selling, general and administrative expense. Costs Of Sales And Operating Expenses Costs of sales and operating expenses Distribution and services - A component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. Distribution And Services [Member] Distribution and Services [Member] Shares Outstanding [Abstract] Shares outstanding [Abstract] Undistributed Earnings Reallocated To Restricted Shares. Undistributed Earnings Reallocated To Restricted Shares Undistributed earnings reallocated to restricted shares Number of shares of common stock determined by relating the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Weighted average common stock issued and outstanding Weighted average common stock issued and outstanding (in shares) Other segment disclosure [Abstract] Other segment disclosures [Abstract] Assets other than goodwill that contribute to the future cash flows of both the cash-generating unit under review and other cash-generating units. General corporate assets Refers to amount of general corporate expenses. General corporate expenses General corporate expenses Tabular disclosure of the profit or loss and total assets for other segment information. Schedule Of Other Segment Reporting Information By Segment [Table Text Block] Other Segment Reporting Information Cash paid (received) during the period [Abstract] Cash paid (received) during the period: Other income (expense) included in net income that results in no cash inflows or outflows in the period. Includes noncash adjustments to reconcile net income (loss) to cash provided by (used in) operating activities that are not separately disclosed. Amortization of Major Maintenance Costs Amortization of major maintenance costs Current and future cash outflow to pay for purchases of fixed assets that have occurred. Capital Expenditures Incurred, Paid and Not yet Paid Capital expenditures included in accounts payable Non-cash investing activity: [Abstract] Non-cash investing activity: Refers to the amount related to amortization of unearned compensation. Amortization of unearned compensation Amortization of unearned share-based compensation Refers to coastal transportation of refined petroleum products and black oil. Coastal Transportation [Member] Coastal Transportation [Member] Refers to inland transportation of petrochemical feedstock, chemicals, pressurized products, refined petroleum products, certain black oil, agricultural chemicals and black oil, such as asphalt. Inland Transportation [Member] Inland Transportation [Member] Refers to selling OEM replacement parts and new diesel engines, provides service mechanics and maintains facilities to overhaul and repair diesel engines and ancillary products for marine and on-highway transportation companies, mining and industrial companies. The Company provides engineering and field services, OEM replacement parts and safety-related products to power generation operators and to the nuclear industry, manufactures engine generator and pump packages for power generation operators and municipalities, offers power generation systems customized for specific commercial and industrial applications, and rents equipment including power generation systems, pumps, air compressors, fork lifts and railcar movers. Commercial and Industrial [Member] Commercial and Industrial [Member] Refers to inland pressure tank barges equipped with tanks that may carry any one of a great variety of liquid commodities, such as petroleum and petroleum products, chemicals, and fertilizers. Inland Pressure Tank Barges [Member] Inland Pressure Barges [Member] Refers to the number of maritime (seagoing) vessels acquired. Number of Maritime Vessels Acquired Number of maritime vessels acquired Number of maritime vessels acquired Refers to the entity that is being acquired or purchased in a merger or acquisition. Convoy Servicing Company and Agility Fleet Services, LLC [Member] Convoy [Member] The amount of operating lease right-of-use assets recognized as of the acquisition date. Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease Right-of-Use Assets Operating lease right-of-use assets Amount of current portion of operating lease liabilities, assumed at the acquisition date. Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Operating Lease Liabilities Current portion of operating lease liabilities Other Supplemental Information about Operating Leases [Abstract] Other Supplemental Information about Operating Leases [Abstract] operating leases related to weighted average discount rate and weighted average remaining lease term. Operating Leases, Weighted Average Discount Rate and Remaining Lease Term [Table Text Block] Operating Leases, Weighted Average Discount Rate and Remaining Lease Term Refers to percentage of pension plan defined benefit plan cost increase limit during the period. Pension Plan Defined Benefit Plan Cost Increase Limit Percentage Pension plan defined benefit plan cost increase limit percentage The service period of eligible participants of the employee pension plan who will be grandfathered and not be impacted by the amendment to the pension plan. Employee Pension Plan, Grandfathered Participants, Service Period Service period of participants not impacted by pension plan amendment The age of eligible participants of the employee pension plan who will be grandfathered and not be impacted by the amendment to the pension plan. Employee Pension Plan, Grandfathered Participants, Participant Age Age of plan participants not impacted by pension plan amendment The service period of eligible participants of the employee pension plan who have reached the age of fifty that will be grandfathered and not be impacted by the amendment to the pension plan. Employee Pension Plan, Grandfathered Participants, Participant Service Period Who is Fifty Years Old Service period of participants who are age fifty not impacted by pension plan amendment Higman pension plan for 2020 year. Plan 2020 [Member] Plan 2020 [Member] Higman pension plan for 2019 year. Plan 2019 [Member] Plan 2019 [Member] Refers to the entity that is being acquired or purchased in a merger or acquisition. Higman Marine, Inc [Member] Higman [Member] Refers to the senior notes debt instruments. Senior Notes Series A Due February Twenty Seven Two Thousand Twenty [Member] 2.72% Unsecured Senior Notes [Member] A credit facility arrangement that is repayable in quarterly installments in increasing percentages of the original principal amount of the loan. Term Loan Facility [Member] Term Loan [Member] Refers to inland tank barges equipped with tanks that may carry any one of a great variety of liquid commodities, such as petroleum and petroleum products, chemicals, and fertilizers. Inland Tank Barges [Member] Inland Tank Barges [Member] Refers to a diesel-powered or steam-powered boat used especially on inland waterways to push groups of barges lashed to it in front or on one side or both. Inland Towboats [Member] Inland Towboats [Member] Refers to the entity that is being acquired or purchased in a merger or acquisition. Savage Inland Marine, LLC [Member] Savage Inland Marine, LLC [Member] Refers to the aggregate carrying capacity of a quantity of tank barges as measured in number of barrels. Tank Barge Aggregate Barrel Capacity Aggregate tank barge barrel capacity (in barrels) Estimated percentage of costs related to service costs and other non-lease components. Percentage of Costs related to Service Costs Estimated Percentage of costs relate to service costs for leased towing vessels Amount of lessee's undiscounted obligation for lease payment for operating lease due after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Lessee Operating Lease Liability Payments Due After Year Four Thereafter Employee Stock Award Plan [Abstract] Stock Award Plan Information [Abstract] Represents to director plan of the equity-based compensation arrangement plan. Director Plan [Member] Director Plan [Member] Represents to employee plan of the equity-based compensation arrangement plan. Employee Plan [Member] Employee Stock Award Plan [Member] A claim for damages that is likely to be made and for which it is reasonably possible that there will be an unfavorable outcome, such as a likelihood that lawsuits from parties as yet unidentified will be filed alleging injury from using a product when other parties have successfully sued the entity for such use. Unasserted Claim 1 [Member] Struck by LPG Tanker, the Genesis River [Member] Number of vessels damaged in collision resulting in fuel oil discharge. Number of vessels damaged in collision resulting in fuel oil discharge Refers to the number of maritime (seagoing) vessels. Number of Maritime Vessels Number of vessels involved in collision Term of the guarantee or each group of financial instruments used to support performance by the company and its subsidiaries in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Term of Instrument Under Guarantor Obligations Guarantor obligations, expiration period Amount of income tax expense (benefit) from effect of Coronavirus Aid, Relief, and Economic Security (CARES) Act. Coronavirus Aid Relief And Economic Security Act Income Tax Expense Benefit Tax benefit related to CARES Act A table disclosing the information about earnings (loss) before taxes on income. Income Tax Disclosure [Table] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Income Tax Disclosure [Line Items] Provision for taxes on income [Abstract] Provision (benefit) for taxes on income [Abstract] Number of years net operating losses are carried back. Number of Years Net Operating Losses Carried Back Number of years net operating losses carried