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v3.10.0.1

Revenue - Additional Information (Detail) | 6 Months Ended
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Sep. 30, 2018
Minimum [Member] |
Supply Commitment [Line Items] |
Long-term supply agreements maturity year | 2018
Revenue from contract with customer collection terms | 30 days
Maximum [Member] |
Supply Commitment [Line Items] |
Long-term supply agreements maturity year | 2025
Revenue from contract with customer collection terms | 65 days

X
- Definition Long-term supply agreements maturity year. + References No definition available. + Details
Name: | exp_LongTermSupplyAgreementsMaturityYear
Namespace Prefix: | exp_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Revenue from contract with customer collection terms. + References No definition available. + Details
Name: | exp_RevenueFromContractWithCustomerCollectionTerms
Namespace Prefix: | exp_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- 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_SupplyCommitmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |