Income Taxes	9 Months Ended
Income Taxes	Jun. 28, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act (the “Act”) was enacted in the United States and significantly revised the U.S. corporate income tax laws. Given the significance of the legislation, the SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), which allows registrants to record provisional amounts during a one year “measurement period” like that used when accounting for business combinations. As of December 22, 2018, we have completed our accounting for the tax effects of the enactment of the Act. For the deferred tax balances, we remeasured the U.S. deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. The Company’s revised remeasurement resulted in cumulative charges to income tax expense of $144.4 million for the measurement period. The Act calls for a one-time tax on deemed repatriation of foreign earnings. This one-time transition tax is based on our total post-1986 earnings and profits (E&P) of certain of our foreign subsidiaries. In the current reporting period, the Company filed its tax return which reflected the transition tax. The net tax liability after considering foreign tax credits resulted in a tax liability of $0.8 million. In addition, the Company recorded $104.2 million in cumulative valuation expense charges during the measurement period with respect to certain foreign tax credit deferred tax assets as a result of the Tax Act and CH2M integration. The Company’s effective tax rates from continuing operations for the three months ended June 28, 2019 and June 29, 2018 were (2.1)% and 21.3%, respectively. The Company’s effective tax rates from continuing operations for the nine months ended June 28, 2019 and June 29, 2018 were 4.3% and 58.5%, respectively. The Company’s effective tax rate from continuing operations for the three months ended June 28, 2019 was lower than the effective tax rate for continuing operations for the three months ended June 29, 2018 primarily due to a favorable discrete benefit of $21.7 million as a result of an election made to defer net operating losses under final regulations, resulting in the utilization of additional previously fully valued foreign tax credits, combined with lower pre-tax book income from continuing operations in the third quarter of fiscal 2019. The effective tax rate for the nine months ended June 28, 2019 was lower primarily due to $54.8 million in net discrete expense during the nine months ended June 29, 2018 mainly comprised of $14.0 million from the impact of the remeasurement of deferred taxes for the Act, $52.5 million for an increase to the valuation allowance related to certain foreign tax credits and an offsetting tax benefit of $5.7 million for a federal hurricane credit. Comparatively, in the nine months ended June 28, 2019, the Company had a $62.6 million discrete benefit, predominantly comprised of $37.4 million for a remeasurement of the Company's deferred tax liability for unremitted earnings to account for the change in expected manner of recovery and an additional benefit of $21.7 million as a result of an election made to defer net operating losses under final regulations, resulting in utilization of previously fully reserved foreign tax credits. See Note 7- Sale of Energy, Chemicals and Resources ("ECR") Business for further information on the Company's discontinued operations reporting for the sale of the ECR business. The amount of income taxes the Company pays is subject to ongoing audits by tax jurisdictions around the world. In the normal course of business, the Company is subject to examination by tax authorities throughout the world, including such major jurisdictions as Australia, Canada, India, the Netherlands, the United Kingdom and the United States. Our estimate of the potential outcome of any uncertain tax issue is subject to our assessment of the relevant risks, facts, and circumstances existing at the time. The Company believes that it has adequately provided for reasonably foreseeable outcomes related to these matters. However, future results may include favorable or unfavorable adjustments to our estimated tax liabilities in the period the assessments are made or resolved, which may impact our effective tax rate. It is reasonably possible that, during the next twelve months, we may realize a decrease in our uncertain tax positions of approximately $16.3 million as a result of concluding various tax audits and closing tax years.