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Retirement Plans - Additional Information (Detail) - USD ($) | 12 Months Ended
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Dec. 28, 2018 | Dec. 29, 2017 | Dec. 30, 2016
Retirement Plan Disclosure [Line Items] |  |  |
Defined Contribution Plan Employer Contribution Percentage Of Eligible Wages | 7.00% |  |
Defined Contribution Plan Employer Contribution Annual Vesting Percentage | 20.00% |  |
Defined Contribution Plan Employer Contribution Annual Vesting Period | 5 years |  |
Pension and Other Postretirement Benefits Cost (Reversal of Cost) | $ 8,419,000 | $ 7,914,000 | $ 7,761,000

X
- Definition Percentage of employer's contributions to a defined contribution plan that vests in a given year. + References No definition available. + Details
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Namespace Prefix: | expo_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of years until employer's contribution to a defined contribution plan fully vest. + References No definition available. + Details
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Namespace Prefix: | expo_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined contribution plan employer contribution percentage of eligible wages. + References No definition available. + Details
Name: | expo_DefinedContributionPlanEmployerContributionPercentageOfEligibleWages
Namespace Prefix: | expo_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Amount of cost (reversal of cost) for pension and other postretirement benefits. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration