XML 79 R67.htm IDEA: XBRL DOCUMENT
v3.21.2

Other Nonoperating Income, Net - Additional Information (Detail) - Other Nonoperating Income, Net - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2021 | Sep. 30, 2020
Component of Other Income And Expense [Line Items] |  |  |
Reduction in pension expense | $ 3.9 | $ 11.8 | $ 8.9
Third-party railroad track maintenance expense |  |  | $ 5.6

X
- Definition Component of other operating income and expense. + References No definition available. + Details
Name: | mlm_ComponentOfOtherOperatingIncomeAndExpenseLineItems
Namespace Prefix: | mlm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Third-party railroad track maintenance expense. + References No definition available. + Details
Name: | mlm_ThirdPartyRailroadTrackMaintenanceExpense
Namespace Prefix: | mlm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expense (reversal of expense) for net periodic benefit cost components, excluding service cost component, of defined benefit plan. Amount includes, but is not limited to, interest cost, expected (return) loss on plan asset, amortization of prior service cost (credit), amortization of (gain) loss, amortization of transition (asset) obligation, settlement (gain) loss, curtailment (gain) loss and certain termination benefits. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919 + Details
Name: | us-gaap_NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_OtherNonoperatingIncomeExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |