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Significant Accounting Policies - Additional Information (Detail) | 9 Months Ended
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Sep. 30, 2018 Facility State Segment
Significant Accounting Policies [Line Items] |
Number of states with aggregates business sales by destination | State | 30
Number of reportable segments | Segment | 3
Minimum [Member] |
Significant Accounting Policies [Line Items] |
Number of quarries and yards | Facility | 300

X
- Definition Number of quarries and yards. + References No definition available. + Details
Name: | mlm_NumberOfQuarriesAndYards
Namespace Prefix: | mlm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of states with aggregates business sales by destination. + References No definition available. + Details
Name: | mlm_NumberOfStatesWithAggregatesBusinessSalesByDestination
Namespace Prefix: | mlm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Significant accounting policies. + References No definition available. + Details
Name: | mlm_SignificantAccountingPoliciesLineItems
Namespace Prefix: | mlm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of segments reported by the entity. A reportable segment is 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. + References No definition available. + Details
Name: | us-gaap_NumberOfReportableSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |