Summarizes Cost And Estimated Fair Value Of Short Term Fixed Income Securities (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 03, 2014	Jan. 03, 2014
Fair Value Measurements [Line Items]
Due within one year, Amortized Cost	$ 18,873
Due between one and two years, Amortized Cost	7,104
Total Amortized Cost	25,977
Due within one year, Estimated Fair Value	18,897
Due between one and two years, Estimated Fair Value	7,112
Total Estimated Fair Value	$ 26,009	$ 33,171

Available for sale securities short term investments amortized cost due in year one.

No definition available.

Name:	expo_AvailableForSaleSecuritiesShortTermInvestmentsAmortizedCostDueInYearOne
Namespace Prefix:	expo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Available For Sale Securities Short Term Investments Amortized Cost Due In Year Two

+ References

No definition available.

+ Details

Name:	expo_AvailableForSaleSecuritiesShortTermInvestmentsAmortizedCostDueInYearTwo
Namespace Prefix:	expo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Available For Sale Securities Short Term Investments Estimated Fair Value Due In Year One

+ References

No definition available.

+ Details

Name:	expo_AvailableForSaleSecuritiesShortTermInvestmentsEstimatedFairValueDueInYearOne
Namespace Prefix:	expo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Available For Sale Securities Short Term Investments Estimated Fair Value Due In Year Two

+ References

No definition available.

+ Details

Name:	expo_AvailableForSaleSecuritiesShortTermInvestmentsEstimatedFairValueDueInYearTwo
Namespace Prefix:	expo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	expo_FairValueMeasurementsLineItems
Namespace Prefix:	expo_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph g

-Article 7

+ Details

Name:	us-gaap_ShortTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant