Debt instrument maturity date year.

No definition available.

Name:	mlm_DebtInstrumentMaturityDateYear
Namespace Prefix:	mlm_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_CreditFacilityAxis=mlm_RevolvingFacilityDueTwentyTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_SixPointSixZeroPercentSeniorNotesDueTwentyEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_FourPointTwoFivePercentSeniorNotesDueTwentyTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_SevenPercentDebenturesDueTwentyTwentyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_ThreePointFourFiveZeroPercentSeniorNotesDueTwentyTwentySevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_ThreePointFiveZeroZeroPercentSeniorNotesDueTwentyTwentySevenMember
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Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_SixPointTwoFivePercentSeniorNotesDueTwentyThirtySevenMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_FourPointTwoFiveZeroPercentSeniorNotesDueTwentyFourtySevenMember
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Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_FloatingRateSeniorNotesDueTwentyNineteenMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_FloatingRateSeniorNotesDueTwentyTwentyMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_FloatingRateSeniorNotesDueTwentySeventeenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mlm_TradeReceivableCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt (Parenthetical) (Detail)	12 Months Ended
Long-Term Debt (Parenthetical) (Detail)	Dec. 31, 2017	Dec. 20, 2017	Dec. 31, 2016
Revolving Facility, Due 2022
Debt Instrument [Line Items]
Maturity year	2022
Credit Facility interest rate			1.86%
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Maturity year	2018
Interest rate on notes	6.60%	6.60%
Interest rate	6.81%
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Maturity year	2024
Interest rate on notes	4.25%
Interest rate	4.25%
7% Debentures, Due 2025
Debt Instrument [Line Items]
Maturity year	2025
Interest rate on notes	7.00%
Interest rate	7.12%
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year	2027
Interest rate on notes	3.45%
Interest rate	3.47%
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Maturity year	2027
Interest rate on notes	3.50%
Interest rate	3.53%
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Maturity year	2037
Interest rate on notes	6.25%
Interest rate	6.45%
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Maturity year	2047
Interest rate on notes	4.25%
Interest rate	4.27%
Floating Rate Notes, Due 2019
Debt Instrument [Line Items]
Maturity year	2019
Interest rate	2.13%
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Maturity year	2020
Interest rate	2.10%
Floating Rate Notes, Due 2017
Debt Instrument [Line Items]
Maturity year	2017
Interest rate			2.10%
Trade Receivable Facility
Debt Instrument [Line Items]
Credit Facility interest rate			1.34%