Property Plant and Equipment Net (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property Plant And Equipment [Abstract]
Land and land improvements	$ 849,704mlm_LandAndLandImprovementsGross	$ 728,396mlm_LandAndLandImprovementsGross
Mineral reserves and interests	990,438us-gaap_MineralPropertiesGross	461,587us-gaap_MineralPropertiesGross
Buildings	157,233us-gaap_BuildingsAndImprovementsGross	118,655us-gaap_BuildingsAndImprovementsGross
Machinery and equipment	3,568,342us-gaap_MachineryAndEquipmentGross	2,575,340us-gaap_MachineryAndEquipmentGross
Construction in progress	125,959us-gaap_ConstructionInProgressGross	92,906us-gaap_ConstructionInProgressGross
Gross property, plant and equipment	5,691,676us-gaap_PropertyPlantAndEquipmentGross	3,976,884us-gaap_PropertyPlantAndEquipmentGross
Less allowances for depreciation, depletion and amortization	(2,288,906)	(2,177,643)
Total	$ 3,402,770us-gaap_PropertyPlantAndEquipmentNet	$ 1,799,241us-gaap_PropertyPlantAndEquipmentNet

Land and land improvements gross.

No definition available.

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- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

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- Definition

Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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- Definition

Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

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- Definition

Carrying amount at the balance sheet date of mineral properties, gross of adjustments.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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