Contractual Guarantees, Litigation, Investigations, and Insurance	12 Months Ended
	Sep. 27, 2019
Contractual Guarantees, Litigation, Investigations, and Insurance [Abstract]
Contractual Guarantees Litigation Investigations And Insurance	Contractual Guarantees, Litigation, Investigations and Insurance In the normal course of business, we make contractual commitments some of which are supported by separate guarantees; and on occasion we are a party in a litigation or arbitration proceeding. The litigation or arbitration in which we are involved primarily includes personal injury claims, professional liability claims and breach of contract claims. Where we provide a separate guarantee it is strictly in support of the underlying contractual commitment. Guarantees take various forms including surety bonds required by law, or standby letters of credit ("LOC") (also referred to as “bank guarantees”) or corporate guarantees given to induce a party to enter into a contract with a subsidiary. Standby LOCs are also used as security for advance payments or in various other transactions. The guarantees have various expiration dates ranging from an arbitrary date to completion of our work (e.g., engineering only) to completion of the overall project. See Note 16- Commitments and Contingencies and Derivative Financial Instruments for more information surrounding LOCs and surety bonds. We maintain insurance coverage for most insurable aspects of our business and operations. Our insurance programs have varying coverage limits depending upon the type of insurance, and include certain conditions and exclusions which insurance companies may raise in response to any claim that the Company brings. We have also elected to retain a portion of losses and liabilities that occur through the use of various deductibles, limits, and retentions under our insurance programs. As a result, we may be subject to a future liability for which we are only partially insured or completely uninsured. We intend to mitigate any such future liability by continuing to exercise prudent business judgment in negotiating the terms and conditions of the contracts which the Company enters with its clients. Our insurers are also subject to business risk and, as a result, one or more of them may be unable to fulfill their insurance obligations due to insolvency or otherwise. Additionally, as a contractor providing services to the U.S. federal government we are subject to many types of audits, investigations and claims by, or on behalf of, the government including with respect to contract performance, pricing, cost allocations, procurement practices, labor practices and socioeconomic obligations. Furthermore, our income, franchise and similar tax returns and filings are also subject to audit and investigation by the Internal Revenue Service, most states within the U.S., as well as by various government agencies representing jurisdictions outside the U.S. Our Consolidated Balance Sheets include amounts representing our probable estimated liability relating to such claims, guarantees, litigation, audits and investigations. We perform an analysis to determine the level of reserves to establish for insurance-related claims that are known and have been asserted against us, and for insurance-related claims that are believed to have been incurred based on actuarial analysis, but have not yet been reported to our claims administrators as of the respective balance sheet dates. We include any adjustments to such insurance reserves in our consolidated results of operations. Insurance recoveries are recorded as assets if recovery is probable and estimated liabilities are not reduced by expected insurance recoveries. The Company believes, after consultation with counsel, that such guarantees, litigation, U.S. government contract-related audits, investigations and claims and income tax audits and investigations should not have a material adverse effect on our consolidated financial statements, beyond amounts currently accrued. On September 30, 2015, Nui Phao Mining Company Limited (“NPMC”) commenced arbitration proceedings against Jacobs E&C Australia Pty Limited (“Jacobs E&C”) in Singapore before the Singapore International Arbitration Centre. Jacobs E&C was engaged by NPMC for the provision of management, design, engineering, and procurement services for a Nui Phao mine/mineral processing project in Vietnam as part of the Company’s Energy, Chemicals & Resources (“ECR”) line of business. A three-week hearing on the merits concluded on December 15, 2017. On March 28, 2019, the arbitration panel issued a decision finding against Jacobs E&C and awarding damages to NPMC of approximately $95.0 million. NPMC subsequently asserted an additional claim for interest, costs and attorneys' fees for approximately $70.0 million, which the Company disputed. On June 28, 2019, the Company filed an application in Singapore to set aside the award. In addition, NPMC filed an application to enforce the award in Australia. On August 30, 2019, NPMC and Jacobs E&C settled all of the foregoing proceedings. Under the terms of the settlement, Jacobs E&C made a payment to NPMC in the amount of $130.0 million. The settlement otherwise remains confidential. The Company expects that a portion of the settlement amount is subject to recovery from insurance; however, the Company currently has not recognized any income for related insurance recoveries. Under the terms of the sale of the Company’s ECR business to Worley on April 26, 2019, the Company has retained liability with respect to this matter. In 2012, CH2M HILL Australia Pty Limited, a subsidiary of CH2M, entered into a 50 /50 integrated joint venture with Australian construction contractor UGL Infrastructure Pty Limited. The joint venture entered into a Consortium Agreement with General Electric and GE Electrical International Inc. The Consortium was awarded a subcontract by JKC Australia LNG Pty Limited for the engineering, procurement, construction and commissioning of a 360 MW Combined Cycle Power Plant for INPEX Operations Australia Pty Limited at Blaydin Point, Darwin, NT, Australia. In January 2017, the Consortium terminated the Subcontract because of JKC’s repudiatory breach and demobilized from the work site. JKC claimed the Consortium abandoned the work and itself purported to terminate the Subcontract. The Consortium and JKC are now in dispute over the termination. In August 2017, the Consortium filed an International Chamber of Commerce arbitration against JKC and is seeking compensatory damages in the amount of approximately $530.0 million for repudiatory breach or, in the alternative, seeking damages for unresolved contract claims and change orders. JKC has provided a preliminary estimate of the monetary value of its claims, which we believe will result in alleged damages in excess of $1.7 billion, and has drawn on bonds. This draw on bonds does not impact the Company's ultimate liability. A hearing on this matter is scheduled to begin in February 2020 and no decision is expected before 2021. In September 2018, JKC filed a declaratory judgment action in Western Australia alleging that the entities which executed parent company guaranties for the Consortium, including CH2M Hill Companies, Ltd., have an obligation to pay JKC’s ongoing costs to complete the project after termination. A hearing on that matter was held on March 12 and 13, 2019, and a decision in favor of the Consortium was issued. JKC has appealed the decision. If the Consortium is found liable, these matters could have a material adverse effect on the Company’s business, financial condition, results of operations and /or cash flows, particularly in the short term. However, the Consortium has denied liability and is vigorously defending these claims and pursuing its affirmative claims against JKC, and based on the information currently available, the Company does not expect the resolution of this matter to have a material adverse effect on the Company’s business, financial condition, results of operations or cash flows, in excess of the current reserve for this matter. See Note 5- Business Combinations for further information relating to CH2M contingencies. On December 22, 2008, a coal fly ash pond at the Kingston Power Plant of the Tennessee Valley Authority (“TVA”) was breached, releasing fly ash waste into the Emory River and surrounding community. In February 2009, TVA awarded a contract to the Company to provide project management services associated with the clean-up. All remediation and dredging were completed in August 2013 by other contractors under direct contracts with TVA. The Company did not perform the remediation, and its scope was limited to program management services. Certain employees of the contractors performing the cleanup work on the project filed lawsuits against the Company beginning in August 2013, alleging they were injured due to the Company’s failure to protect the plaintiffs from exposure to fly ash, and asserting related personal injuries. There are currently six separate cases, the primary case, Greg Adkisson, ET AL v. Jacobs Engineering Group Inc., case No. 3:13-CV-505-TAV-HBG in the US District Court for the Eastern District of Tennessee, consists of 10 consolidated cases. This case and the related cases involve several hundred plaintiffs that have been filed against the Company by employees of the contractors. The cases are at various stages of litigation, and several of the cases are currently stayed by the court pending resolution of other cases. In May 2019, Roane County filed a claim against TVA and the Company alleging that they misled the public about risks associated with the released fly ash. This matter is scheduled for trial in 2021. In addition, in November 2019, a resident of Roane County filed a purported class action against TVA and the Company alleging they failed to adequately warn local residents about risks associated with the released fly ash. There has been no finding of liability against the Company or that any of the alleged illnesses are the result of exposure to fly ash in any of the cases. The Company disputes the claims asserted in all of the above matters and is vigorously defending these claims.