Business Combinations - Additional Information (Detail)	1 Months Ended
Aug. 31, 2020 Plant
Business Combinations [Abstract]
Business combination, number of ready mixed concrete operations acquired	4

Business Combination, number of ready mixed concrete operations acquired.

No definition available.

Name:	mlm_BusinessCombinationNumberOfReadyMixedConcreteOperationsAcquired
Namespace Prefix:	mlm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration