Contractual Guarantees, Litigation, Investigations, and Insurance	12 Months Ended
	Sep. 27, 2024
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" and 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 18- 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 is asserted by or against the Company. We have also elected to retain a portion of certain losses, claims and liabilities that occur through the use of various deductibles, limits, and retentions under our insurance programs and utilize a number of internal financing mechanisms for these self-insurance arrangements, including the operation of certain captive insurance entities. 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. 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 ("JKC") 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 (the "Legacy CH2M Matter"). The subcontract was terminated in January 2017. In or around August 2017, the Consortium commenced an arbitration. On April 12, 2022, JKC and the Consortium entered into a confidential deed of settlement (“Settlement Agreement”). Under the terms of the Settlement Agreement, CH2M, as guarantor of CH2M Australia PTY Limited’s obligations with respect to the subcontract with JKC, made a cash payment to JKC in April 2022 of AUD 640 million (or approximately $475 million using mid-April 2022 exchange rates). As a result of the settlement agreement, additional pre-tax charges of $91.3 million were recorded during the year ended September 29, 2022 for this matter (over amounts previously reserved and reported in long-term Other Deferred Liabilities in the Company's Consolidated Balance Sheet). The Settlement Agreement provided for a release of claims between JKC and each member of the Consortium, and in connection with this agreement the members of the Consortium also waived all claims against each other and their respective parent guarantors relating to the project. During the fourth quarter of fiscal 2022, the Company recorded a receivable for certain expected third-party recoveries equal to approximately $27 million before tax. The Company received the payment during fiscal 2023.