Basis of Presentation	9 Months Ended
Basis of Presentation	Jul. 02, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Unless the context otherwise requires: •References herein to “Jacobs” are to Jacobs Engineering Group Inc. and its predecessors; •References herein to the “Company”, “we”, “us” or “our” are to Jacobs Engineering Group Inc. and its consolidated subsidiaries; and •References herein to the “Group” are to the combined economic interests and activities of the Company and the persons and entities holding noncontrolling interests in our consolidated subsidiaries. The accompanying consolidated financial statements and financial information included herein have been prepared pursuant to the interim period reporting requirements of Form 10-Q. Consequently, certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) have been condensed or omitted. Readers of this Quarterly Report on Form 10-Q should also read our consolidated financial statements and the notes thereto included in our Annual Report on Form 10-K for the fiscal year ended October 2, 2020 (“2020 Form 10-K”). In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary for a fair presentation of our consolidated financial statements at July 2, 2021, and for the three and nine month periods ended July 2, 2021. Our interim results of operations are not necessarily indicative of the results to be expected for the full fiscal year. Effective the beginning of fiscal first quarter 2020, the Company adopted ASU 2016-02, Leases ("ASC 842"), including the subsequent ASU's that amended and clarified the related guidance. The Company adopted ASC 842 using a modified retrospective approach, and accordingly the new guidance was applied to leases that existed or were entered into after the first day of adoption without adjusting the comparative periods presented. Please refer to Note-13 Leases for required disclosures related to leases. On March 2, 2021, Jacobs completed the strategic investment of a 65% interest in PA Consulting, a UK-based leading innovation and transformation consulting firm. The total consideration paid by the Company was $1.7 billion, funded through cash on hand, a new term loan and draws on the Company's existing revolver. Further, in connection with the transaction, an estimated additional $267 million had not yet been distributed at April 2, 2021 due to continuing employment requirements. Consequently, this amount represented compensation expense incurred related to the acquisition that was expensed in the second quarter, and was reflected in selling, general and administrative expense on the consolidated income statement for the six month period ended April 2, 2021. During the third quarter of fiscal 2021, an amount of $5.6 million of the above estimated charges was forfeited by employees that left the Company before payment, and as such, was recognized in earnings in the three month period ended July 2, 2021. The updated amount of $261 million is reflected in earnings and cash from operations for the nine month period ended July 2, 2021. The remaining 35% interest is held by PA Consulting employees, whose redeemable noncontrolling interests had a fair value of $582.4 million on the closing date, including subsequent purchase accounting adjustments. PA Consulting is accounted for as a consolidated subsidiary and as a separate operating segment under U.S. GAAP accounting rules. See Note 12- Borrowings for more discussion on the financing for the transaction. On November 24, 2020, a subsidiary of Jacobs completed the acquisition of Buffalo Group, a leader in advanced cyber and intelligence solutions. The Company paid total consideration of $190.1 million, which was comprised of approximately $182.4 million in cash to the former owners of Buffalo Group and contingent consideration of $7.7 million, which is expected to be settled in fiscal 2022. During the third fiscal quarter, the Company recorded an adjustment to the contingent consideration of $3.8 million to selling, general and administrative expense, resulting in contingent consideration of $3.9 million at July 2, 2021. In conjunction with the acquisition, the Company assumed the Buffalo Group's debt of approximately $7.7 million. The Company repaid all of the assumed Buffalo Group debt by the end of the first fiscal quarter of 2021. The acquisition of Buffalo Group allows Jacobs to further expand its cyber and intelligence solutions offering to government clients. On March 6, 2020, a subsidiary of Jacobs completed the acquisition of the nuclear consulting, remediation and program management business of John Wood Group, a U.K.-based energy services company, for an enterprise value of £246 million, or approximately $317.9 million, less cash acquired of $24.3 million, as updated for additional working capital adjustments. The John Wood Group nuclear business allows Jacobs to further expand its lifecycle nuclear services business. The Company has recorded its final purchase price allocation associated with the acquisition, which is summarized in Note 16- Other Business Combinations. On April 26, 2019, Jacobs completed the sale of its Energy, Chemicals and Resources ("ECR") business to Worley Limited, a company incorporated in Australia ("Worley"), for a purchase price of $3.4 billion consisting of (i) $2.8 billion in cash plus (ii) 58.2 million ordinary shares of Worley, subject to adjustments for changes in working capital and certain other items (the “ECR sale”). As a result of the ECR sale, substantially all ECR-related assets and liabilities were sold (the "Disposal Group"). We determined that the Disposal Group should be reported as discontinued operations in accordance with ASC 210-05, Discontinued Operations because their disposal represents a strategic shift that had a major effect on our operations and financial results. As such, the financial results of the ECR business are reflected in our unaudited Consolidated Statements of Earnings as discontinued operations for all periods presented. As of October 2, 2020, all of the ECR business to be sold under the terms of the ECR sale had been conveyed to Worley and as such, no amounts remain held for sale. For further discussion, see Note 17- Sale of Energy, Chemicals and Resources ("ECR") Business to the consolidated financial statements.