Cash received from SpinCo business Proceeds from Divestiture of Businesses Selling, general and administrative expense Disposal Group, Including Discontinued Operation, General and Administrative Expense, Net of Reserves Disposal Group, Including Discontinued Operation, General and Administrative Expense, Net of Reserves Statistical Measurement [Domain] Statistical Measurement [Domain] Other deferred liabilities Deferred Long-Term Liability Charges Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Award Timing Predetermined Award Timing Predetermined [Flag] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Interest Rate Swap Interest Rate Swap [Member] Net (Loss) from discontinued operations allocated to common stock for EPS calculation Undistributed Earnings (Loss) from Discontinued Operations Available to Common Shareholders, Basic 2025 Stock Repurchase Program Two Thousand Twenty-Five Stock Repurchase Program [Member] Two Thousand Twenty-Five Stock Repurchase Program Equity in earnings of operating ventures, net of return on capital distributions Net (loss) income from equity method investments Income (Loss) from Equity Method Investments Australia and New Zealand Australia and New Zealand [Member] Australia and New Zealand [Member] Tabular List, Table Tabular List [Table Text Block] Income Tax (Expense) Benefit: Other Comprehensive Income (Loss), Tax Net Earnings Per Share: Earnings Per Share, Basic [Abstract] Discontinued Operation, Working Capital Adjustment, Receivable Discontinued Operation, Working Capital Adjustment, Receivable Discontinued Operation, Working Capital Adjustment, Receivable First Step Up Date First Step Up Date [Member] First Step Up Date 5.9% Bonds, due 2033 5.90% Bonds [Member] 5.90% Bonds Unbilled receivables and other Unbilled Contracts Receivable Business combination share issued (in shares) Business Combination, Consideration Transferred, Equity Interest, Share Issued, Number of Shares Schedule of Dividends Declared Dividends Declared [Table Text Block] New Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Business combination, additional deferred consideration payable to acquiree employees Business Combination, Additional Deferred Consideration, Payable to Acquiree Employees Business Combination, Additional Deferred Consideration, Payable to Acquiree Employees Cash contributions made during the first six months of fiscal 2026 Payment for Pension Benefits Accounts payable Increase (Decrease) in Accounts Payable Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Schedule of Disposal Groups, Including Discontinued Operations Disposal Groups, Including Discontinued 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Schedule of Segment Reporting Information, by Segment [Table Text Block] Diluted (Loss) from Discontinuing Operations Per Share (in dollars per share) Diluted Net (Loss) from Discontinuing Operations Per Share (in dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Remaining performance obligation, amounts Revenue, Remaining Performance Obligation, Amount Miscellaneous Other Assets, Miscellaneous, Noncurrent Adjustment to Compensation, Amount Adjustment to Compensation Amount Remaining performance obligation, percentage Revenue, Remaining Performance Obligation, Percentage Step Up Date Axis [Domain] Step Up Date Axis [Domain] Step Up Date Axis [Domain] Miscellaneous other assets Increase (Decrease) in Other Operating Assets Stock based compensation Share-Based Payment Arrangement, Noncash Expense Employee Stock Option Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Total Jacobs stockholders’ equity Equity, Attributable to Parent Insider Trading Policies and Procedures [Line Items] Allocated share-based compensation expense Share-Based Payment Arrangement, Expense Net (Loss) Earnings from continuing operations allocated to common stock for EPS calculation Undistributed Earnings (Loss) from Continuing Operations Available to Common Shareholders, Basic Common stock, authorized (in shares) Common Stock, Shares Authorized Surety Bond Surety Bond [Member] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current Assets: Assets, Current [Abstract] Total liabilities and equity Liabilities and Equity Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Change in Net Pension Obligation Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Equity method investment retained, shares transferred to escrow (in shares) Discontinued Operation, Shares Transferred to Escrow Discontinued Operation, Shares Transferred to Escrow Cash and Cash Equivalents, including Restricted Cash, at the Beginning of the Period Cash and Cash Equivalents, including Restricted Cash, at the End of the Period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Cover page. Cover [Abstract] Discontinued Operations Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Maximum Maximum [Member] Intangible assets Disposal Group, Including Discontinued Operations, Amortization of Intangible Assets Disposal Group, Including Discontinued Operations, Amortization of Intangible Assets Interest rate, increase (decrease) over period (as a percent) Debt Instrument, Interest Rate, Increase (Decrease) Net Loss Attributable to Noncontrolling Interests Net Income (Loss) Attributable to Noncontrolling Interest Schedule of Restructuring and Other Activities by Major Type of Costs Schedule Of Major Type Of Restructuring Cost [Table Text Block] Schedule of major type of restructuring Beginning balance Ending balance Total Finite-Lived Intangible Assets, Net Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Other expense, net Disposal Group, Including Discontinued Operation, Other Income, Net of Expenses Disposal Group, Including Discontinued Operation, Other Income, Net of Expenses Net (Loss) Earnings of the Group from Continuing Operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Cash in employee benefit trust Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Employee Benefit Trust, Cash Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Employee Benefit Trust, Cash Business combination, additional consideration deferred, estimated equity value Business Combination, Additional Consideration Deferred, Estimated Equity Value Business Combination, Additional Consideration Deferred, Estimated Equity Value Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount PA Consulting Redeemable Noncontrolling Interests Business Combination [Text Block] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Property, equipment and improvements Depreciation, Depletion and Amortization, Nonproduction (Loss) Earnings from Continuing Operations Before Taxes (Loss) Earnings from Continuing Operations Before Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Schedule of Estimated Fair Value of Outstanding Bonds Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Disposals of property and equipment and other assets Proceeds from Sale of Property, Plant, and Equipment Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Gross (loss) profit Disposal Group, Including Discontinued Operation, Gross Profit (Loss) Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Repurchase of redeemable noncontrolling interests Redemption of redeemable noncontrolling interests relating to the PA Consulting Transaction Payments for Repurchase of Redeemable Noncontrolling Interest Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Net Comprehensive (Loss) Income Attributable to Jacobs Comprehensive Income (Loss), Net of Tax, Attributable to Parent Disposal Group Name [Domain] Disposal Group Name [Domain] Name Measure Name Beginning balance Ending balance Restructuring Reserve Net (Loss) Earnings Attributable to Jacobs from Continuing Operations Net (Loss) Earnings Attributable to Jacobs from Continuing Operations Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Letter of Credit Letter of Credit [Member] Unsecured Revolving Credit Facility March 16, 2026 Unsecured Revolving Credit Facility March 16, 2026 [Member] Unsecured Revolving Credit Facility March 16, 2026 Operating lease liabilities Operating Lease, Liability, Current Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] Equity, Attributable to Noncontrolling Interest [Roll Forward] Finite-lived Intangible Assets [Roll Forward] Finite-Lived Intangible Assets [Roll Forward] Class of Stock [Line Items] Class of Stock [Line Items] Deferred income tax liabilities Deferred Income Tax Liabilities, Net Document Fiscal Period Focus Document Fiscal Period Focus Net Loss Attributable to Jacobs from Discontinued Operations Net Loss Attributable to Jacobs from Discontinued Operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Award Timing Method Award Timing Method [Text Block] Basic Net (Loss) Earnings from Continuing Operations Per Share (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Net earnings (loss) Net Income (Loss), Excluding Portion Attributable to Noncontrolling Interest Net Income (Loss), Excluding Portion Attributable to Noncontrolling Interest Award Type Award Type [Axis] Foreign Currency Translation Adjustment Accumulated Foreign Currency Adjustment Attributable to Parent [Member] 2025 Term Loan Facility 2025 Term Loan Facility [Member] 2025 Term Loan Facility Assets Assets Assets Cash Flows from Investing Activities: Cash Provided by (Used in) Investing Activity, Continuing Operation [Abstract] Investment, Name [Domain] Investment, Name [Domain] 2027 Finite-Lived Intangible Asset, Expected Amortization, Year One Trading Symbol Trading Symbol Infrastructure & Advanced Facilities Infrastructure & Advanced Facilities [Member] Infrastructure & Advanced Facilities Geographical [Domain] Geographical [Domain] Entity Address, City or Town Entity Address, City or Town Sub Facility Of Swing Line Loans Sub Facility Of Swing Line Loans [Member] Sub facility of swing line loans. Cash Flows from Operating Activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] 6.35% Bonds, due 2028 6.35% Bonds [Member] 6.35% Bonds Non-deductible compensation related charge associated with the PA Consulting acquisition Effective Income Tax Rate Reconciliation, Nondeductible Expense, Incentive Compensation Related To Acquisition, Amount Effective Income Tax Rate Reconciliation, Nondeductible Expense, Incentive Compensation Related To Acquisition, Amount Effect of Exchange Rate Changes Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Total Expected Contributions To Funded Pension Plans Expected contributions to funded pension plans. Consideration transferred Business Combination, Consideration Transferred Restructuring costs Restructuring Costs Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] 2030 Finite-Lived Intangible Asset, Expected Amortization, Year Four Entity Emerging Growth Company Entity Emerging Growth Company Disposal group, including discontinued operation, foreign tax indemnity reserve release Disposal Group, Including Discontinued Operation, Foreign Tax Indemnity Reserve Release Disposal Group, Including Discontinued Operation, Foreign Tax Indemnity Reserve Release Dividend declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Amounts billed, net Billed Contracts Receivable Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Revenues Revenues Revenues from External Customers Revenue from Contract with Customer, Including Assessed Tax Less: Deferred Financing Fees Debt Issuance Costs, Net Gain (loss) on derivatives, before taxes Derivative, Gain (Loss) on Derivative, Net 2026 Term Loan Facility - Five-year 2026 Term Loan Facility - 5Y [Member] 2026 Term Loan Facility - 5Y State and local income taxes Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Equity method investments Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Combination [Domain] Business Combination [Domain] Discontinued operation, receivable balance collected Discontinued Operation, Receivable Balance Collected Discontinued Operation, Receivable Balance Collected Common stock, outstanding (in shares) Common Stock, Shares, Outstanding Schedule Of Finite Lived Intangible Assets And Liabilities [Table] Schedule Of Finite Lived Intangible Assets And Liabilities [Table] Schedule of finite lived intangible assets and liabilities. PEO PEO [Member] Receivables and Contract Assets Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Interest income Investment Income, Interest Finite-Lived Intangible Assets and Liabilites [Line Items] Finite Lived Intangible Assets And Liabilities [Line Items] Finite lived intangible assets and liabilities. United States UNITED STATES Changes in assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Guarantor obligations, carrying value Guarantor Obligations, Current Carrying Value Schedule of Estimated Amortization Expense of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] 2025 Term Loan Facility - USD Portion 2025 Term Loan Facility - USD Portion [Member] 2025 Term Loan Facility - USD Portion Retained Earnings Retained Earnings [Member] 2021 Term Loan Facility 2021 Term Loan Facility [Member] 2021 Term Loan Facility Effective interest rate (as a percent) Debt Instrument, Interest Rate, Effective Percentage Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Pension and retiree medical plan liability, deferred taxes Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment and Disposals, Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment and Disposals, Tax Income Statement [Abstract] Income Statement [Abstract] Income Tax Benefit (Expense) from Continuing Operations Income Tax Expense (Benefit) Debt instrument, basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Basic (Loss) from Discontinuing Operations Per Share (in dollars per share) Basic Net (Loss) from Discontinuing Operations Per Share (in dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Cash flow hedges Derivative gains (losses), deferred tax expense (benefit) Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Preferred stock, issued (in shares) Preferred Stock, Shares Issued Intangibles, net Intangible Assets, Net (Excluding Goodwill) Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Fixed Rate Date Fixed Rate Date [Member] Fixed Rate Date Direct cost of contracts Disposal Group, Including Discontinued Operation, Costs of Goods Sold, Net of Expense Reversal Disposal Group, Including Discontinued Operation, Costs of Goods Sold, Net of Expense Reversal Repurchase and issuance of redeemable noncontrolling interests Repurchase and Issuance of Redeemable Noncontrolling Interests Repurchase and Issuance of Redeemable Noncontrolling Interests Change in cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Diluted Net (Loss) Earnings from Continuing Operations Per Share (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Total Jacobs Stockholders’ Equity Parent [Member] Net (Loss) Earnings of the Group Net (Loss) Earnings of the Group Net Earnings (Loss) of the Group Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Business Combination [Table] Business Combination [Table] Derivative notional amount Derivative, Notional Amount Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations and Disposal Groups [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Redemption price, basis spread over variable rate Debt Instrument, Redemption Price, Basis Spread On Variable Rate Debt Instrument, Redemption Price, Basis Spread On Variable Rate Restructuring and Other Charges Restructuring and Related Activities Disclosure [Text Block] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Redemption price percentage Debt Instrument, Redemption Price, Percentage Accrued liabilities Accrued Liabilities, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net cash (used for) provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Repayments of short-term borrowings Repayments of Short-Term Debt Debt instrument, term (in years) Debt Instrument, Term Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Redeemable Noncontrolling interests redemption value adjustment Noncontrolling Interest, Period Increase (Decrease) Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Subsequent Event Subsequent Event [Member] Goodwill Balance at the beginning of the period Balance at the end of the period Goodwill Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] 2026 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Equity Components [Axis] Equity Components [Axis] Redeemable Noncontrolling interests redemption value adjustment Noncontrolling Interest, Change in Redemption Value Amortization of previously unrecognized items Defined Benefit Plan, Amortization Of Gain (Loss) And Prior Service Cost (Credit) Defined Benefit Plan, Amortization Of Gain (Loss) And Prior Service Cost (Credit) Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Net Loss (Earnings) Attributable to Redeemable Noncontrolling Interests Net Loss (Earnings) Attributable to Redeemable Noncontrolling Interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest, Continuing Operations Net Income (Loss) Attributable to Redeemable Noncontrolling Interest, Continuing Operations Stock issued during period, spinoff transaction ( in shares) Stock Issued During Period, Shares, Spinoff Transaction Stock Issued During Period, Shares, Spinoff Transaction Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] 2023 Stock Repurchase Program Two Thousand Twenty-Three Stock Repurchase Program [Member] Two Thousand Twenty-Three Stock Repurchase Program Other Performance Measure, Amount Other Performance Measure, Amount Debt issuance costs Payments of Debt Issuance Costs Entity Address, State or Province Entity Address, State or Province Dividends Dividends, Common Stock Fair Value and Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Total current liabilities Liabilities, Current 2026 Term Loan Facility - Three-year 2026 Term Loan Facility - 3Y [Member] 2026 Term Loan Facility - 3Y Cumulative amounts incurred to date Restructuring and Related Cost, Cost Incurred to Date Derivative Instrument [Axis] Derivative Instrument [Axis] Individual: Individual [Axis] Vesting [Axis] Vesting [Axis] Earnings Per Share Reconciliation [Abstract] Earnings Per Share Reconciliation [Abstract] Initial consideration distributed in cash Other Payments to Acquire Businesses Cash dividends to shareholders Payments of Ordinary Dividends, Common Stock Additional paid-in capital Additional Paid in Capital, Common Stock Other Other Restructuring [Member] Net cash used for investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Revenue, remaining performance obligation, expected timing of satisfaction, period (in months) Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Document Fiscal Year Focus Document Fiscal Year Focus Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Ownership interest of employees (as a percent) Subsidiary, Ownership Percentage, Noncontrolling Owner Repayments of long-term borrowings Repayments of Long-Term Debt Effective income tax rate (as a percent) Effective Income Tax Rate Reconciliation, Percent Entity Interactive Data Current Entity Interactive Data Current Depreciation and amortization: Depreciation, Depletion and Amortization [Abstract] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Pre-tax transaction costs Business Combination, Acquisition-Related Cost, Expense Schedule of Certain Information Regarding Cash Contributions Defined Benefit Plans Company Cash Contributions Table [Table Text Block] Tabular disclosure of cash contributions to company pension plans Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Equity [Abstract] Equity [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Total Issued Letters of Credit Total Issued Letters of Credit [Member] Total Issued Letters of Credit Schedule of Acquired Intangibles in Accompanying Consolidated Balance Sheets Schedule Of Finite Lived Intangible Assets And Liabilities [Table Text Block] Schedule Of Finite Lived Intangible Assets And Liabilities Loss on investment in equity securities Debt and Equity Securities, Gain (Loss) Segment Information Segment Reporting Disclosure [Text Block] Schedule of Goodwill [Table] Goodwill [Table] Preference share effect on basic earnings per share (in dollars per share) Dilutive Securities, Effect on Basic Earnings Per Share, Preference Share Dilutive Securities, Effect on Basic Earnings Per Share, Preference Share Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Ownership [Domain] Ownership [Domain] Schedule of Components of Net Periodic Pension Benefit Expense Recognized in Earnings Schedule of Net Benefit Costs [Table Text Block] Change in cash flow hedges, net of deferred taxes Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Amortization Amortization of Intangible Assets Amortization of Intangible Assets Selling, general and administrative expenses Selling, General and Administrative Expense Deferred income tax assets Deferred Income Tax Assets, Net Schedule of Accumulated Other Comprehensive Loss After-Tax Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Total other noncurrent assets Other Assets, Noncurrent Entity Central Index Key Entity Central Index Key Settlement Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Other Comprehensive (Loss) Income: Other Comprehensive Income (Loss), before Tax [Abstract] PEO Name PEO Name Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Other Restructuring and Related Cost, Realized Gain (Loss) Restructuring and Related Cost, Realized Gain (Loss) Revolving Credit Facility Revolving Credit Facility [Member] Revenue Recognition Period [Axis] Revenue Recognition Period [Axis] Revenue Recognition Period Foreign income tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Outside Services Outside Services Outside Services [Member] Outside services. Arrangement Duration Trading Arrangement Duration Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Transition services agreement, expenses incurred Discontinued Operation, Transition Services Agreement, Expenses (Income) Discontinued Operation, Transition Services Agreement, Expenses (Income) Discontinued operation, remaining shares held in escrow (in shares) Discontinued Operation, Remaining Shares Held In Escrow Discontinued Operation, Remaining Shares Held In Escrow Capital contributions to equity investees, net of return of capital distributions Payments for (Proceeds from) Investments Share-Based Payment Arrangement, Tranche One Share-Based Payment Arrangement, Tranche One [Member] Segments Segments [Axis] Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Redeemable Noncontrolling interests Temporary Equity, Carrying Amount, Attributable to Parent PA Consulting Group Limited PA Consulting Group Limited [Member] PA Consulting Group Limited Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Europe Europe [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Total Shares Repurchased and Retired (in shares) Stock Repurchased and Retired During Period, Shares Discontinued Operations, Disposed of by Means Other than Sale, Spinoff Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] Shares issued during period, spinoff, conversion ratio (in shares) Shares Issued During Period, Spinoff, Conversion Ratio Shares Issued During Period, Spinoff, Conversion Ratio ASSETS Assets [Abstract] SpinCo Business SpinCo Business [Member] SpinCo Business Long-term debt Long-Term Debt, Excluding Current Maturities Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Balance Sheet Location [Axis] Statement of Financial Position Location, Balance [Axis] 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Three Vesting [Domain] Vesting [Domain] Component: Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Debt Instrument [Axis] Debt Instrument [Axis] Pension and Other Postretirement Benefit Plans Retirement Benefits [Text Block] Fair Value and Fair Value Measurements Fair Value Disclosures [Text Block] Business Combination [Line Items] Business Combination [Line Items] Loss on extinguishment of debt Loss on extinguishment of debt Gain (Loss) on Extinguishment of Debt Credit Facility [Domain] Credit Facility [Domain] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Award vesting percentage Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Interest rate and cross currency swap gains to be reclassified during the next 12 months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Accumulated Other Comprehensive Income (Loss) Total AOCI Attributable to Parent [Member] Investment, Name [Axis] Investment, Name [Axis] Interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Operating (Loss) Profit Disposal Group, Including Discontinued Operation, Operating Income (Loss) Long-term operating lease liabilities Operating Lease, Liability, Noncurrent Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Ownership [Axis] Ownership [Axis] Current Assets Assets, Current [Member] Assets, Current Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Fair Value as of Grant Date Award Grant Date Fair Value Accounts receivable from unconsolidated joint ventures accounted for under the equity method Accounts Receivable, after Allowance for Credit Loss Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Total net periodic pension benefit expense recognized Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Treasury Lock Treasury Lock [Member] Schedule of Long-term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Capital stock: Capital Stock [Abstract] Capital Stock [Abstract] Stock compensation plans (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Distribution adjustments relating to SpinCo Business Stockholders' Equity Note, Spinoff Transaction Document Quarterly Report Document Quarterly Report Estimated Fair Value Long-Term Debt, Fair Value Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Number of operating segments Number of Operating Segments Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Accounting Standards Update and Change in Accounting Principle [Abstract] Discontinued Operation, Transition Services Agreement, Income (Expenses) Discontinued Operation, Transition Services Agreement, Income (Expenses) Discontinued Operation, Transition Services Agreement, Income (Expenses) Interest cost Defined Benefit Plan, Interest Cost Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Restatement Determination Date: 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