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Document And Entity Information - shares
3 Months Ended
Dec. 30, 2016
Jan. 31, 2017
Document And Entity Information [Abstract]    
Entity Registrant Name JACOBS ENGINEERING GROUP INC /DE/  
Trading Symbol jec  
Entity Central Index Key 0000052988  
Current Fiscal Year End Date --09-29  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Dec. 30, 2016  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   121,071,296