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Pension and Employee Benefit Plans - Additional Information (Detail) $ in Millions | Dec. 31, 2017 USD ($)
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Compensation And Retirement Disclosure [Abstract] |
Contributions to pension plans | $ 8.5

X
- Definition Defined benefit plan employer contributions current. + References No definition available. + Details
Name: | exp_DefinedBenefitPlanEmployerContributionsCurrent
Namespace Prefix: | exp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration