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Pension and Employee Benefit Plans - Additional Information (Detail) $ in Millions | Sep. 30, 2017 USD ($)
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Compensation And Retirement Disclosure [Abstract] |
Anticipated contributions to pension plans during fiscal third quarter | $ 8.5

X
- Definition Defined benefit plan expected future employer contributions next fiscal quarter. + References No definition available. + Details
Name: | exp_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalQuarter
Namespace Prefix: | exp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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