| Cover Page | Nov. 25, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Nov. 25, 2019 |
| Entity Registrant Name | Jacobs Engineering Group Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-7463 |
| Entity Tax Identification Number | 95-4081636 |
| Entity Address, Address Line One | 1999 Bryan Street |
| Entity Address, Address Line Two | Suite 1200 |
| Entity Address, City or Town | Dallas |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75201 |
| City Area Code | 214 |
| Local Phone Number | 583-8500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | JEC |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000052988 |
| Amendment Flag | false |
