XML 38 R1.htm IDEA: XBRL DOCUMENT v2.4.0.8
Document And Entity Information
 6 Months Ended
Jul. 04, 2014
Aug. 01, 2014
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jul. 04, 2014  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus Q2  
Entity Registrant Name EXPONENT INC  
Entity Central Index Key 0000851520  
Current Fiscal Year End Date --01-02  
Entity Filer Category Accelerated Filer  
Trading Symbol EXPO  
Entity Common Stock, Shares Outstanding   13,087,900