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Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Equity [Abstract] |  |  |  |
Balance at beginning of period | $ 40 | $ 53 | $ 41 | $ 54
Tax effect of other comprehensive earnings | 0 | 0 | (1) | (1)
Balance at end of period | $ 40 | $ 53 | $ 40 | $ 53

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- Definition Accumulated other comprehensive loss, noncurrent deferred tax assets, other comprehensive earnings, tax effect, pension and postretirement benefit plans. + References No definition available. + Details
Name: | mlm_AccumulatedOtherComprehensiveLossNoncurrentDeferredTaxAssetsOtherComprehensiveEarningsTaxEffectPensionAndPostretirementBenefitPlans
Namespace Prefix: | mlm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Accumulated other comprehensive loss, noncurrent deferred tax assets, pension and postretirement benefit plans. + References No definition available. + Details
Name: | mlm_AccumulatedOtherComprehensiveLossNoncurrentDeferredTaxAssetsPensionAndPostretirementBenefitPlans
Namespace Prefix: | mlm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- References No definition available. + Details
Name: | us-gaap_EquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration