Total investments Investments at fair value Investments at fair value EBP, Investment, Fair Value Maximum Maximum [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Vanguard Master Trust (Note D) Vanguard Master Trust Vanguard Master Trust [Member] Vanguard Master Trust Self-directed brokerage accounts Assets in Bank of America, N.A. Self-Directed Brokerage Accounts EBP, Self-Directed Brokerage Account [Member] Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Accrued expenses Accrued expenses EBP, Accrued Expense Plan interest in Master Trust EBP, Nonconsolidated, Plan Interest in Master Trust [Member] Benefits Payable [Line Items] Benefits Payable [Line Items] Benefits Payable Reconciliation of Net Assets Available for Benefits to Form 5500 EBP, Reconciliation of Financial Statement to Form 5500 [Table Text Block] Government bonds US Treasury and Government [Member] Unfunded Commitment EBP, Fair Value, Investment, NAV, Unfunded Commitment Total liabilities Total liabilities EBP, Liability Amendment Flag Amendment Flag EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] EBP, Description of Plan and Accounting Change [Abstract] Receivables EBP, Receivable [Abstract] Schedule of Plan's Investments at Fair Value in Recurring Basis and the Plan's Investments at NAV per share EBP, Investment, Fair Value and NAV [Table Text Block] EBP 055 EBP 055 EBP 055 [Member] EBP 055 Asset-backed securities Asset-Backed Securities [Member] Investments [Domain] Investments [Domain] Northern Trust All Country World ex-U.S. Index Fund Northern Trust All Country World ex-U.S. Index Fund [Member] Northern Trust All Country World ex-U.S. Index Fund Registered Investment Companies: Registered Investment Companies [Member] Registered Investment Companies EBP, Schedule of Reportable Transaction [Abstract] Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Participants EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover In-kind distributions EBP, Investment Sold, Excluding Plan Interest in Master Trust, In-Kind Distribution EBP, Investment Sold, Excluding Plan Interest in Master Trust, In-Kind Distribution Net appreciation in fair value of investments and Investment gain from self-directed brokerage accounts Net appreciation in fair value of investments and income Net depreciation in fair value of shares bought and sold, as well as held during the year EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Plan number EBP, Plan Number Contributions
Pending
Correction in VFCP EBP, Schedule of Delinquent Participant Contribution, Pending Correction in VFCP Retirement date funds Retirement Date Funds [Member] Retirement Date Funds EBP, Schedule of Asset Held for Investment [Abstract] Stable Value Master Trust (Note F) Stable Value Master Trust Stable Value Master Trust [Member] Stable Value Master Trust EBP, Form 5500 Caption, Net Assets [Abstract] EBP, Form 5500 Caption, Net Assets [Abstract] EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Total additions EBP, Change in Net Asset Available for Benefit, Increase Allowance for credit loss EBP, Note Receivable from Participant, Allowance for Credit Loss Total investments EBP, Asset Held for Investment Benefits Payable [Table] Benefits Payable [Table] Benefits Payable Document Information [Line Items] Document Information [Line Items] INVESTMENT IN AECOM DC RETIREMENT PLANS VANGUARD MASTER TRUST INVESTMENT IN AECOM DC RETIREMENT PLANS SMA MASTER TRUST INVESTMENT IN AECOM DC RETIREMENT PLANS STABLE VALUE MASTER TRUST EBP, Master Trust [Text Block] Index funds Index Funds [Member] Index Funds Level 2 Fair Value, Inputs, Level 2 [Member] Stocks Equity Securities [Member] Corporate bonds Corporate Bond Securities [Member] Net increase per Form 5500 EBP, Form 5500 Caption, Net Income (Loss) Net purchases (redemptions) EBP, Change in Net Asset Available for Benefit, Decrease From Net Purchases (Redemptions) EBP, Change in Net Asset Available for Benefit, Decrease From Net Purchases (Redemptions) NET INCREASE Net increase per financial statements EBP, Change in Net Asset Available for Benefit, Increase (Decrease) RELATED PARTY TRANSACTIONS EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Abstract] Total receivables EBP, Receivable Employer contributions EBP, Employer Contribution, Receivable Net appreciation in fair value of investments and Investment gain from self-directed brokerage accounts EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Unrealized Gain (Loss) on Investment Participant automatic deferral rate (percent) EBP, Participant Contribution, Automatic, Deferral Rate Benefits paid to participants (Note A and Note G) EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Plan investments in AECOM DC Retirement Plans (Note B): EBP, Investment, Plan Interest in Master Trust, Fair Value EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Master Trust Name [Axis] EBP, Master Trust Name [Axis] EBP, Master Trust Name EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Table] SMA Master Trust (Note E) SMA Master Trust SMA Master Trust [Member] SMA Master Trust EBP, Master Trust [Table] EBP, Master Trust [Table] Total Fair Value Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Document Type Document Type Loan repayment period (up to) EBP, Note Receivable from Participant, Account, Maximum Repayment Period EBP, Note Receivable from Participant, Account, Maximum Repayment Period Administrative expenses Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Investment Expense Interest rate on participant loans (percent) EBP, Asset Held for Investment, Participant Loan, Interest Rate EBP, Reconciliation of Financial Statement to Form 5500 [Abstract] Collective investment trusts (measured at NAV) Northern Trust Collective Short-term Investment Fund T. Rowe Structured Research Common Collective Trust [Member] BENEFITS PAYABLE Benefits Payable [Text Block] Benefits Payable Fair Value Measurements Fair Value Measurements [Policy Text Block] Fair Value Measurements Cash and cash equivalents Cash and Cash Equivalents [Member] DEDUCTIONS FROM NET ASSETS ATTRIBUTED TO: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Notes receivable from participants (Notes A and B) EBP, Note Receivable from Participant Entity Registrant Name Entity Registrant Name Schedule of Net Assets of the Stable Value Master Trust EBP, Master Trust [Table Text Block] LIABILITIES: EBP, Liability [Abstract] EBP, Schedule of Delinquent Participant Contribution [Table] EBP, Schedule of Delinquent Participant Contribution [Table] Participant vesting period in employer contributions EBP, Employer Contribution Vesting Service Period EBP, Employer Contribution Vesting Service Period Subsequent Events EBP, Subsequent Event [Policy Text Block] Maximum annual participant pre-tax contribution rate, as percentage of compensation (percent) EBP, Participant Contribution, Pretax, Maximum Annual Compensation To Eligible Bonus Compensation, Percentage EBP, Participant Contribution, Pretax, Maximum Annual Compensation To Eligible Bonus Compensation, Percentage Mortgage-backed securities Collateralized Mortgage Obligations [Member] Notes Receivable from Participants EBP, Note Receivable from Participant [Policy Text Block] Net investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Other Other EBP, Other Receivable Net Assets Available for Benefits Beginning of year End of year Net assets available for benefits per the financial statements EBP, Net Asset Available for Benefit CONTRIBUTIONS: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Net assets available for benefits per Form 5500 EBP, Form 5500 Caption, Net Assets Forfeited non-vested accounts used to reduce future employer contributions and / or pay administrative expenses of the Plan EBP, Forfeited Nonvested Account, Decrease From Administrative Expense And Employer Contributions EBP, Forfeited Nonvested Account, Decrease From Administrative Expense And Employer Contributions Investments measured at NAV Fair Value Measured at Net Asset Value Per Share [Member] Plan's interest in Master Trust (percent) EBP, Interest in Master Trust, Percentage Net Assets Available for Benefits EBP, Statement of Net Asset Available for Benefit [Line Items] EIN Entity Tax Identification Number Net change in amounts allocated to withdrawing participants EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) from Deemed Distribution Legal Entity [Axis] Legal Entity [Axis] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Mutual funds Mutual Fund [Member] Total Fully Corrected
Under VFCP and PTE
2002-51 EBP, Schedule of Delinquent Participant Contribution, Corrected Payable to participants EBP, Liability to Participant Investments sold during the period EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Master Trust Name [Domain] EBP, Master Trust Name [Domain] EBP, Master Trust Name Participant loan limit EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount FAIR VALUE MEASUREMENTS EBP, Investment, Fair Value and NAV [Text Block] Minimum loan amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Company's match allocation to AECOM common stock (percent) EBP, Employee Benefit Plan, Employer Contribution Matching Percent, Company Stock Allocation EBP, Employee Benefit Plan, Employer Contribution Matching Percent, Company Stock Allocation Investments—at fair value (Notes B and C) Total investments at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Level 1 Fair Value, Inputs, Level 1 [Member] EBP, Investment, Fair Value and NAV [Abstract] Total assets EBP, Asset ASSETS: EBP, Asset [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] ADDITIONS TO NET ASSETS ATTRIBUTED TO: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Payment of Benefits EBP, Payment to Participant [Policy Text Block] EBP, Master Trust [Line Items] EBP, Master Trust [Line Items] Basis of Accounting EBP, Basis of Accounting [Policy Text Block] Receivable for securities sold EBP, Investment Sale, Receivable Plan investments held (in shares) EBP, Investment, Number of Shares AECOM Common Stock Common Stock [Member] Plan Termination [Line Items] Plan Termination [Line Items] Plan Termination EBP, Master Trust [Abstract] Use of Estimates EBP, Use of Estimate [Policy Text Block] AECOM common stock issued by the Company to the Plan EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Plan Sponsor's Non-Cash Issuance EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Plan Sponsor's Non-Cash Issuance SCHEDULE OF ASSETS (HELD AT END OF YEAR) EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] RISKS AND UNCERTAINTIES EBP, Risk and Uncertainty [Text Block] Benefits payable Amounts allocated to withdrawing participants EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Allocation to Withdrawing Participant, Not yet Paid Employer EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash EBP, Schedule of Delinquent Participant Contribution [Line Items] EBP, Schedule of Delinquent Participant Contribution [Line Items] EBP, Form 5500 Caption, Benefit Payment and Payments to Provide Benefits [Abstract] EBP, Form 5500 Caption, Benefit Payment and Payments to Provide Benefits [Abstract] Accrued income EBP, Investment Income, Receivable Minimum Minimum [Member] Arrowstreet International Equity Fund Arrowstreet International Equity Fund [Member] Arrowstreet International Equity Fund Investment Type [Axis] Investment Type [Axis] INTEREST INCOME ON NOTES RECEIVABLE FROM PARTICIPANTS EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Loan interest rate, spread on prime rate (percent) EBP, Participant Loan, Basis Spread On Variable Rate EBP, Participant Loan, Basis Spread On Variable Rate Interest and dividends Interest and dividend income EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Company's match allocation to participant's selected investment allocations (percent) EBP, Employee Benefit Plan, Employer Contribution Matching Percent, Participant Allocation EBP, Employee Benefit Plan, Employer Contribution Matching Percent, Participant Allocation EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] DESCRIPTION OF THE PLAN EBP, Description of Plan [Text Block] Changes in Net Asset Available for Benefit EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] AECOM common stock EBP, Employer, Common Stock [Member] INVESTMENT INCOME: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment, Identifier [Axis] Investment, Identifier [Axis] Administrative expenses Record keeping and administrative expense EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Table] EBP, Risk and Uncertainty [Table] Plan Termination [Table] Plan Termination [Table] Plan Termination Eligible compensation contributed by Participant that is matched (percent) EBP, Employer Contribution, Participant Compensation Matched, Percentage Investment gain from self-directed brokerage accounts EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Realized Gain (Loss) on Investment EBP, Statement of Change in Net Asset Available for Benefit [Abstract] T. Rowe Price Structured Research Common Trust Fund T. Rowe Price Structured Research Common Trust [Member] T. Rowe Price Structured Research Common Trust Contributions
Corrected
Outside VFCP EBP, Schedule of Delinquent Participant Contribution, Corrected Outside VFCP EBP, Tax Status [Table] EBP, Tax Status [Table] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Dividend income recorded EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment TOTAL PLAN INVESTMENTS EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Delinquent deposits of employee deferrals and loan repayments EBP, Schedule of Delinquent Participant Contribution, Transferred Late to Plan Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Due to broker for securities purchased EBP, Liability for Investment Purchase EBP, Tax Status [Abstract] Plan interest in the investment income of the AECOM DC Retirement Plans: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Change in Plan Interest in Master Trust EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] Plan Expenses EBP, Expense [Policy Text Block] RECONCILIATION OF FINANCIAL STATEMENTS TO FORM 5500 EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] Notes receivable from participants EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Investment Valuation and Income Recognition EBP, Investment [Policy Text Block] Total investment income Total investment income Net purchases (redemptions) EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Investment Income (Loss), before Investment Expense PLAN TERMINATION EBP, Plan Termination [Text Block] Entity Central Index Key Entity Central Index Key EBP, Risk and Uncertainty [Abstract] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] Master Trust EBP, Nonconsolidated, Master Trust [Member] Fidelity Growth Company Commingled Fund FIdelity Growth Company Commingled Fund [Member] FIdelity Growth Company Commingled Fund Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] SIGNIFICANT ACCOUNTING POLICIES EBP, Summary of Accounting Policy [Text Block] Investments acquired during the period EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost SCHEDULE OF DELINQUENT PARTICIPANT CONTRIBUTIONS EBP, Schedule of Delinquent Participant Contribution [Text Block] TAX STATUS EBP, Tax Status [Text Block] Participant loan limit as a percentage of vested account balance (percent) EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Plan Termination [Abstract] Plan Termination Document Information [Table] Document Information [Table] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] Contributions
Not corrected EBP, Schedule of Delinquent Participant Contribution, Not Corrected Benefits Payable [Abstract] Benefits Payable [Abstract] Entity [Domain] Entity [Domain] EARNEST Partners Emerging Market Fund EARNEST Partners Emerging Market Fund [Member] EARNEST Partners Emerging Market Fund EBP, Forfeited Nonvested Account EBP, Forfeited Nonvested Account Company's match (percent) EBP, Employer Contribution, Matching Percentage EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table]