SCHEDULE OF ASSETS (HELD AT END OF YEAR) (Details) - EBP 055	12 Months Ended
Dec. 31, 2025 USD ($) shares
EBP, Schedule of Asset Held for Investment [Line Items]
EIN	61-1088522
Plan number	055
Notes receivable from participants	$ 23,208,585
Total investments	2,962,774,084
AECOM Common Stock
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	446,479,546
Registered Investment Companies:
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	573,111,973
T. Rowe Structured Research
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	1,400,227,423
Assets in Bank of America, N.A. Self-Directed Brokerage Accounts
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	$ 519,746,557
Minimum
EBP, Schedule of Asset Held for Investment [Line Items]
Interest rate on participant loans (percent)	4.25%
Maximum
EBP, Schedule of Asset Held for Investment [Line Items]
Interest rate on participant loans (percent)	9.50%
Investment, Identifier [Axis]: Participation in common or collective trusts \| EARNEST Partners SMID Cap Core Fund
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	$ 246,860,186
Plan investments held (in shares) \| shares	23,495,761
Investment, Identifier [Axis]: Participation in common or collective trusts \| Fidelity Growth Company Commingled Fund
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	$ 568,253,219
Plan investments held (in shares) \| shares	6,382,716
Investment, Identifier [Axis]: Participation in common or collective trusts \| T.Rowe Structured Research
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	$ 585,114,018
Plan investments held (in shares) \| shares	5,827,248
Investment, Identifier [Axis]: Registered Investment Companies \| BlackRock Advisors BIF Money Fund
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	$ 4,733,927
Plan investments held (in shares) \| shares	4,733,927
Investment, Identifier [Axis]: Registered Investment Companies \| Dodge & Cox U.S. Equity
EBP, Schedule of Asset Held for Investment [Line Items]
TOTAL PLAN INVESTMENTS	$ 568,378,046
Plan investments held (in shares) \| shares	34,260,280

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Exchange Act
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Amount of total assets in schedule of asset held for investment of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, current value of investment, participant loan, and plan interest in master trust.

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Amount, after deemed distribution, of participant loan in schedule of asset held for investment of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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Number of shares or units of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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Plan number of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), in three-digit numeric format.

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