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Schedule of Estimated Effective Income Tax Rate (Detail)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Income Tax Disclosure [Abstract]    
Continuing operations (15.20%)us-gaap_EffectiveIncomeTaxRateContinuingOperations 26.70%us-gaap_EffectiveIncomeTaxRateContinuingOperations
Discontinued operations   6.30%mlm_EffectiveIncomeTaxRateDiscontinuedOperations
Consolidated overall (15.20%)mlm_EffectiveIncomeTaxRateConsolidatedOverall 26.70%mlm_EffectiveIncomeTaxRateConsolidatedOverall