Number of options to renew lease.

No definition available.

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Namespace Prefix:	expo_
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Balance Type:	na
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- Definition

Number of states in which entity has lease arrangements.

+ References

No definition available.

+ Details

Name:	expo_NumberOfStatesInWhichEntityHasLeaseArrangements
Namespace Prefix:	expo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of land held.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- 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_LesseeLeaseDescriptionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Income earned by providing the use of assets to an outside party in exchange for a payment or series of payments that is nonoperating in nature.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7)
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=expo_OfficeLaboratoryAndStorageSpaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
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- Details

Name:	us-gaap_LeaseContractualTermAxis=expo_PhoenixArizonaMember
Namespace Prefix:
Data Type:	na
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Period Type:

Leases - Additional Information (Detail)	3 Months Ended		9 Months Ended
Leases - Additional Information (Detail)	Oct. 02, 2020 USD ($) a State Option	Sep. 27, 2019 USD ($)	Oct. 02, 2020 USD ($) a State Option	Sep. 27, 2019 USD ($)
Other Income [Member]
Lessee Lease Description [Line Items]
Rental Income \| $	$ 750,000	$ 721,000	$ 2,611,000	$ 2,202,000
Office, Laboratory, and Storage Space [Member]
Lessee Lease Description [Line Items]
Number of States in which Entity Has Lease Arrangements \| State	13		13
Office, Laboratory, and Storage Space [Member] \| Minimum
Lessee Lease Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year		1 year
Office, Laboratory, and Storage Space [Member] \| Maximum
Lessee Lease Description [Line Items]
Lessee, Operating Lease, Term of Contract	10 years		10 years
Phoenix Arizona
Lessee Lease Description [Line Items]
Lessee, Operating Lease, Term of Contract	30 years		30 years
Area of Land \| a	147		147
Number of Options to Renew Lease \| Option	2		2
Lessee, Operating Lease, Renewal Term	15 years		15 years