Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Jun. 28, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies 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 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. We record in the Consolidated Balance Sheets amounts representing our estimated liability relating to such guarantees, litigation and insurance claims. Guarantees are accounted for in accordance with ASC 460-10, Guarantees, at fair value at the inception of the guarantee. At June 28, 2019 and September 28, 2018, the Company had issued and outstanding approximately $359.0 million and $446.6 million, respectively, in LOCs and $1.16 billion and $870.3 million, respectively, in 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 is asserted by or against the Company. We have also elected to retain a portion of losses and liabilities that occur through using 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 United States, as well as by various government agencies representing jurisdictions outside the United States. 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, as well as 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 has asserted a claim for interest, costs and attorneys' fees for approximately $70.0 million, which the Company intends to dispute. The award otherwise remains confidential. A hearing on the interest and cost claim is scheduled to begin on October 28, 2019. On June 28, 2019, the Company filed an application in Singapore to set aside the award. In addition, NPMC has filed an application to enforce the award in Australia. A hearing on that application is scheduled to begin on September 4, 2019. In connection with a temporary stay of the proceedings to enforce the award, the Company delivered a bank guarantee in the amount of $95.0 million. The Company expects that a portion of the award is subject to recovery from insurance, however, the Company currently has not accrued a receivable for related insurance recoveries. Under the terms of the sale of the Company’s ECR business to WorleyParsons on April 26, 2019, the Company has retained liability with respect to this matter. The Company recorded pre-tax charges in discontinued operations for estimates related to the award and recovery of costs, estimated related interest and attorneys' fees in the amount of $147.0 million in the second quarter of 2019. 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 2020. 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.