Document And Entity Information Debt Instrument, Name [Domain] Statistical Measurement [Axis] Note To Financial Statement Details Textual Note 2 - Earnings Per Common Share Income taxes expense Note 11 - Revenue and Business Segments ecd_NonRule10b51ArrTrmntdFlag Non-Rule 10b5-1 Arrangement Terminated [Flag] Note 2 - Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Details) ecd_NonRule10b51ArrAdoptedFlag Non-Rule 10b5-1 Arrangement Adopted [Flag] Note 11 - Revenue and Business Segments - Operating Revenue and Operating Income by Segment (Details) Depreciation Trading Arrangements, by Individual [Table] Material Terms of Trading Arrangement [Text Block] Notes To Financial Statements Notes To Financial Statements [Abstract] Minimum [Member] Dividends Payable [Table] Statistical Measurement [Domain] Maximum [Member] Schedule of Long-Term Debt Instruments [Table] Debt Instrument [Axis] Cash flows provided by operating activities: Cash flows provided by/(used for) investing activities: us-gaap_StockOptionPlanExpense Stock or Unit Option Plan Expense us-gaap_PurchaseObligationFutureMinimumPaymentsRemainderOfFiscalYear Purchase Obligation, to be Paid, Remainder of Fiscal Year us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash provided by operating activities Cash flows used for financing activities: us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash used for investing activities us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash used for financing activities Salaries, wages and benefits Operating Segments [Member] us-gaap_DividendsCommonStockCash Dividends on common stock Accounting Policies [Abstract] Segments [Domain] Insurance and claims accruals us-gaap_IncreaseDecreaseInInsuranceLiabilities Long-Term Purchase Commitment, Category of Item Purchased [Domain] Category of Item Purchased [Axis] Dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared (in dollars per share) Segments [Axis] Income Statement [Abstract] Cash and cash equivalents and escrow deposit: us-gaap_SharesOutstanding Balance (in shares) Balance (in shares) us-gaap_PurchaseObligationDueInNextTwelveMonths Purchase Obligation, to be Paid, Year One us-gaap_NumberOfOperatingSegments Number of Operating Segments us-gaap_NumberOfReportableSegments Number of Reportable Segments us-gaap_DeferredIncomeTaxExpenseBenefit Deferred income taxes Segment Reporting [Text Block] Net income Net income Net income Adjustments to reconcile net income to net cash provided by operating activities: Segment Reporting [Table Text Block] Preferred stock, $.01 par value per share; 2,000,000 shares authorized; no shares issued and outstanding us-gaap_Liabilities Total liabilities us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders’ equity us-gaap_IncreaseDecreaseInReceivables Receivables Consolidation Items [Axis] Segment Reporting [Table] us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets Prepaid expenses and other us-gaap_ShareBasedCompensation Share-based payment arrangement compensation expense Consolidation Items [Domain] Share-Based Payment Arrangement [Text Block] Changes in other current operating items: us-gaap_IncreaseDecreaseInAccountsPayable Accounts payable Accounting Standards Update and Change in Accounting Principle [Table] us-gaap_PreferredStockSharesIssued Preferred Stock, Shares Issued (in shares) us-gaap_PreferredStockSharesOutstanding Preferred Stock, Shares Outstanding, Ending Balance (in shares) Preferred Stock, Shares Authorized (in shares) Reconciliation of cash and cash equivalents and escrow deposit in the consolidated condensed balance sheets: Supplies and maintenance Amount of expense associated with supplies and maintenance during the period. Supplemental non-cash disclosure: Fair Value, by Balance Sheet Grouping [Table] Preferred Stock, Par or Stated Value Per Share (in dollars per share) Accrued and other current liabilities mrtn_IncreaseDecreaseInAccruedOtherCurrentLiabilities The increase (decrease) during the reporting period in accrued and other current liabilities. us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect Net change in cash and cash equivalents and escrow deposit us-gaap_RelatedPartyTransactionAmountsOfTransaction Related Party Transaction, Amounts of Transaction Accrued and other current liabilities Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Also, including amount of liabilities classified as other, due within one year or the normal operating cycle, if longer. Fuel and fuel taxes Amount of expense associated with fuel and fuel tax expense. Communications and utilities Amount of expense associated with communications and utilities during the period. Related Party Transaction [Table] Related Party Transactions Disclosure [Text Block] us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations Beginning of period End of period Antidilutive Securities, Name [Domain] Statement [Table] mrtn_LineOfCreditFacilityDividendsPaymentMaximum Line of Credit Facility, Dividends Payment, Maximum The maximum amount of dividends that can be paid under the credit facility. Operating ratio Ratio of operating expenses. Statement of Financial Position [Abstract] Operating ratio, net of fuel surcharges Ratio of operating expenses including fuel surcharges. us-gaap_NonoperatingIncomeExpense Other Insurance and claims us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity Intermodal Business Assets [Member] Represents Intermodal business assets. Cash paid for income taxes Uninsured Risk [Member] us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity Line of Credit Facility, Remaining Borrowing Capacity srt_StockRepurchaseProgramAuthorizedAmount1 Share Repurchase Program, Authorized, Amount us-gaap_EscrowDeposit Escrow deposit Product and Service [Domain] Product and Service [Axis] us-gaap_LineOfCredit Long-Term Line of Credit Purchased transportation Costs of purchased transportation and other third-party services incurred to service customers Other noncurrent assets us-gaap_OtherCostAndExpenseOperating Other us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue Lessee, Operating Lease, Liability, to be Paid Revenue Equipment [Member] Represents information pertaining to the "revenue equipment" category of property, plant and equipment. dei_DocumentType Document Type Buildings And Land Office Equipment And Other [Member] Represents information pertaining to buildings and land, office equipment and other. Operating expenses (income): Document Information [Line Items] dei_DocumentQuarterlyReport Document Quarterly Report Document Information [Table] us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities [Axis] dei_EntityInteractiveDataCurrent Entity Interactive Data Current Change in property and equipment not yet paid The increase (decrease) to the amount of future cash outflows to pay for purchases of fixed assets that have occurred. dei_DocumentTransitionReport Document Transition Report us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding Diluted earnings per common share - weighted-average shares and assumed conversions (in shares) Nature of Expense [Axis] Commitments and Contingencies Disclosure [Text Block] Statement [Line Items] Total operating expenses Total operating expenses Common Stock, Shares, Issued (in shares) Common Stock, Shares, Outstanding (in shares) Common Stock, Shares Authorized (in shares) Credit Facility [Member] Credit facility member. Effect of dilutive stock options (in shares) Purchase of Fuel, Tires and Related Services [Member] Represents information about the purchase of fuel and tire services. us-gaap_WeightedAverageNumberOfSharesOutstandingBasic Basic earnings per common share - weighted-average shares (in shares) Tire Purchases [Member] Represents information pertaining to tire purchases. us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1 Share Repurchase Program, Remaining Authorized, Amount Basic earnings per common share (in dollars per share) Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table] Numerator: Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Denominator: Common stock, $.01 par value per share; 192,000,000 shares authorized; 81,661,669 shares at June 30, 2026, and 81,542,174 shares at December 31, 2025, issued and outstanding Dividends [Text Block] Disclosure of information related to dividends paid during the period. Accounts payable mrtn_AdjustmentsToAdditionalPaidInCapitalEmployeeTaxesPaidInExhangeForSharesWitheld Employee taxes paid in exchange for shares withheld The adjustment to APIC satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award. us-gaap_PolicyTextBlockAbstract Accounting Policies Unvested Performance Unit Awards [Member] Unvested performance unit awards member. us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements us-gaap_TableTextBlock Notes Tables Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares) Issuance of common stock from share-based payment arrangement exercises (in shares) Document Fiscal Period Focus Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards mrtn_ClaimLimitAggregateCost Claim Limit, Aggregate Cost The maximum amount an insurer will remember policy holders for covered losses for claims. Document Fiscal Year Focus mrtn_CustomerContractTerm Customer Contract Term (Year) Duration of customer contracts. Amendment Flag Common Stock [Member] mrtn_LiabilityClaimAmount Liability Claim, Amount The claim amount that can be used for the aggregate value of annual claims. Truckload [Member] Truckload member. dei_DocumentPeriodEndDate Document Period End Date Insurance and claims accruals Dedicated [Member] Dedicated segment provides customized transportation solutions tailored to meet individual customers’ requirements, utilizing temperature-controlled trailers, dry vans and other specialized equipment within the United States. Truckload Fuel Surcharge Revenue [Member] Truckload fuel surcharge revenue member. Intermodal [Member] One of the company's segments that transports freight within the US, primarily utilizing our temperature controlled containers or to lesser extent contracted carriers. Long-Lived Asset, Class [Domain] Brokerage [Member] One of the company's segments that arranges for small third party carriers to transport freight for our customers. Also includes MWL revenues. Revenue, Net of Fuel Surcharge [Member] Represents revenue from segment net of fuel surcharge revenue. Legal Entity [Axis] Fuel Surcharge Revenue [Member] Represents revenue from fuel surcharges. Significant Accounting Policies [Text Block] dei_EntityFileNumber Entity File Number Noncurrent operating lease liabilities Entity Tax Identification Number Entity [Domain] Entity Central Index Key dei_EntityRegistrantName Entity Registrant Name dei_EntityCurrentReportingStatus Entity Current Reporting Status Entity Incorporation, State or Country Code Current Fiscal Year End Date dei_EntityFilerCategory Entity Filer Category dei_EntityShellCompany Entity Shell Company dei_EntityEmergingGrowthCompany Entity Emerging Growth Company Capital Addition Purchase Commitments [Member] dei_EntitySmallBusiness Entity Small Business us-gaap_OperatingIncomeLoss Operating income Operating income/(loss) Proceeds from revenue equipment dispositions Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] us-gaap_ContractWithCustomerAssetNet Contract with Customer, Asset, after Allowance for Credit Loss, Total Share Repurchase Program [Table] us-gaap_Revenues Operating revenue Entity Address, State or Province Statement of Stockholders' Equity [Abstract] Entity Address, City or Town Loss Contingency Nature [Axis] Retained earnings Entity Address, Address Line One Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Statement of Cash Flows [Abstract] City Area Code us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation Employee taxes paid in exchange for shares withheld Local Phone Number Entity Address, Postal Zip Code Stockholders’ equity: Title of 12(b) Security Equity Components [Axis] Security Exchange Name Trading Symbol Class of Stock [Axis] Equity Component [Domain] us-gaap_CapitalizedContractCostImpairmentLoss Capitalized Contract Cost, Impairment Loss dei_EntityCommonStockSharesOutstanding Entity Common Stock, Shares Outstanding (in shares) Additional Paid-in Capital [Member] Retained Earnings [Member] Earnings Per Share [Text Block] Escrow deposit Loss Contingency, Nature [Domain] us-gaap_PropertyPlantAndEquipmentNet Net property and equipment Revenue equipment, buildings and land, office equipment and other Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Axis] Property and equipment: us-gaap_PaymentsForProceedsFromOtherInvestingActivities Other Common Stock, Par or Stated Value Per Share (in dollars per share) Share-based payment arrangement compensation expense Long-Lived Asset, Class [Axis] us-gaap_Assets Total assets Deferred income taxes Workers Compensation Liability Claim [Member] Entity's liability claim for workers compensation contingencies. Cash and cash equivalents Cash and cash equivalents Auto Liability Claim [Member] Entity's liability claim for auto contingencies. Fair Value Disclosures [Text Block] us-gaap_GainLossOnDispositionOfAssets Gain on disposition of revenue equipment Gain on disposition of revenue equipment Share-Based Payment Arrangement, Option [Member] Supplemental disclosure of cash flow information: Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Current liabilities: us-gaap_LiabilitiesCurrent Total current liabilities Diluted earnings per common share (in dollars per share) us-gaap_NontradeReceivablesCurrent Other us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards us-gaap_LettersOfCreditOutstandingAmount Letters of Credit Outstanding, Amount mrtn_RefrigeratedContainers Refrigerated Containers The number of refrigerated containers. Trade, net Treasury Stock [Text Block] Tires in service amortization Represents information related to amortization expense for tires in service. mrtn_LossContingencyRangePossibleLossPerClaim Loss Contingency Range Possible Loss Per Claim Amount of possible loss from each claim incurred. Disposal Group Name [Domain] Other Commitments [Table] us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Accumulated depreciation Operating lease assets and liabilities acquired The value of operating lease assets and liabilities recognized in noncash transactions. Interim Period, Costs Not Allocable [Domain] us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest Total stockholders’ equity Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest Income before income taxes us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration Disposal Group, Including Discontinued Operation, Consideration Additional paid-in capital us-gaap_StockholdersEquity Balance Balance Debt Disclosure [Text Block] Prepaid expenses and other mrtn_ReconciliationOfCashAndCashEquivalentsAndEscrowDeposits Total cash and cash equivalents and escrow deposit shown above The total value of cash and cash equivalents including the escrow deposits that was reconciled during the period. us-gaap_PaymentsOfDividendsCommonStock Dividends on common stock Payments of Ordinary Dividends, Common Stock us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Revenue equipment additions Nature of Operation, Product Information, Concentration of Risk [Table] Current assets: us-gaap_LongtermDebtWeightedAverageInterestRate Long-Term Debt, Weighted Average Interest Rate, at Point in Time us-gaap_AssetsCurrent Total current assets ecd_Rule10b51ArrTrmntdFlag Rule 10b5-1 Arrangement Terminated [Flag] Operating revenue Operating revenue ecd_Rule10b51ArrAdoptedFlag Rule 10b5-1 Arrangement Adopted [Flag] Operating taxes and licenses