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Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Equity [Abstract]
Balance at beginning of period	$ 40	$ 53	$ 41	$ 54
Tax effect of other comprehensive earnings	(1)	(1)	(2)	(2)
Balance at end of period	$ 39	$ 52	$ 39	$ 52

X

- Definition

Accumulated other comprehensive loss, noncurrent deferred tax assets, other comprehensive earnings, tax effect, pension and postretirement benefit plans.

+ References

No definition available.

+ Details

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X

- Definition

Accumulated other comprehensive loss, noncurrent deferred tax assets, pension and postretirement benefit plans.

+ References

No definition available.

+ Details

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Namespace Prefix:	mlm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration