| Cover Page | Nov. 23, 2021 | Aug. 17, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | Nov. 23, 2021 | |
| 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 | J | |
| Security Exchange Name | NYSE | |
| Entity Emerging Growth Company | false | |
| Entity Central Index Key | 0000052988 | |
| Amendment Flag | false |
