SEC Info℠  
    Home      Search      My Interests      Help      Sign In      Please Sign In
 
We’re going down soon, to move to a new Data Center today.  We’ll be up ASAP.  Sorry.

AECOM – ‘10-K’ for 9/30/23 – ‘XML’

On:  Tuesday, 11/14/23, at 8:55pm ET   ·   As of:  11/15/23   ·   For:  9/30/23   ·   Accession #:  1104659-23-118329   ·   File #:  0-52423

Previous ‘10-K’:  ‘10-K’ on 11/17/22 for 9/30/22   ·   Latest ‘10-K’:  This Filing   ·   40 References:   

Find Words in Filings emoji
 		  in    Show  and   ↓Hints

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

11/15/23  AECOM                             10-K        9/30/23  124:20M                                    Toppan Merrill/FA

Annual Report   —   Form 10-K

Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-K        Annual Report                                       HTML   4.27M 
 2: EX-21.1     Subsidiaries List                                   HTML     36K 
 3: EX-23.1     Consent of Expert or Counsel                        HTML     32K 
 4: EX-31.1     Certification -- §302 - SOA'02                      HTML     38K 
 5: EX-31.2     Certification -- §302 - SOA'02                      HTML     38K 
 6: EX-32       Certification -- §906 - SOA'02                      HTML     35K 
12: R1          Document and Entity Information                     HTML    101K 
13: R2          Consolidated Balance Sheets                         HTML    184K 
14: R3          Consolidated Balance Sheets (Parenthetical)         HTML     43K 
15: R4          Consolidated Statements of Operations               HTML    171K 
16: R5          Consolidated Statements of Comprehensive Income     HTML     72K 
17: R6          Consolidated Statements of Stockholders' Equity     HTML    103K 
18: R7          Consolidated Statements of Cash Flows               HTML    154K 
19: R8          Significant Accounting Policies                     HTML     59K 
20: R9          New Accounting Pronouncements and Changes in        HTML     37K 
                Accounting                                                       
21: R10         Discontinued Operations, Goodwill, and Intangible   HTML    166K 
                Assets                                                           
22: R11         Revenue Recognition                                 HTML     99K 
23: R12         Property and Equipment                              HTML     65K 
24: R13         Joint Ventures and Variable Interest Entities       HTML    123K 
25: R14         Pension Benefit Obligations                         HTML    579K 
26: R15         Debt                                                HTML     78K 
27: R16         Derivative Financial Instruments and Fair Value     HTML     66K 
                Measurements                                                     
28: R17         Concentration of Credit Risk                        HTML     36K 
29: R18         Leases                                              HTML    151K 
30: R19         Stockholders' Equity                                HTML     40K 
31: R20         Share-Based Payments                                HTML    115K 
32: R21         Income Taxes                                        HTML    214K 
33: R22         Earnings Per Share                                  HTML     49K 
34: R23         Other Financial Information                         HTML     50K 
35: R24         Reclassifications out of Accumulated Other          HTML    114K 
                Comprehensive Loss                                               
36: R25         Commitments and Contingencies                       HTML     47K 
37: R26         Reportable Segments and Geographic Information      HTML    183K 
38: R27         Major Clients                                       HTML     35K 
39: R28         Schedule II: Valuation and Qualifying Accounts      HTML     64K 
40: R29         Significant Accounting Policies (Policies)          HTML     96K 
41: R30         Discontinued Operations, Goodwill, and Intangible   HTML    175K 
                Assets (Tables)                                                  
42: R31         Revenue Recognition (Tables)                        HTML     88K 
43: R32         Property and Equipment (Tables)                     HTML     63K 
44: R33         Joint Ventures and Variable Interest Entities       HTML    119K 
                (Tables)                                                         
45: R34         Pension Benefit Obligations (Tables)                HTML    593K 
46: R35         Debt (Tables)                                       HTML     62K 
47: R36         Derivative Financial Instruments and Fair Value     HTML     59K 
                Measurements (Tables)                                            
48: R37         Leases (Tables)                                     HTML    154K 
49: R38         Income Taxes (Tables)                               HTML    209K 
50: R39         Earnings Per Share (Tables)                         HTML     47K 
51: R40         Other Financial Information (Tables)                HTML     48K 
52: R41         Reclassifications out of Accumulated Other          HTML    113K 
                Comprehensive Loss (Tables)                                      
53: R42         Reportable Segments and Geographic Information      HTML    181K 
                (Tables)                                                         
54: R43         Significant Accounting Policies - Fiscal Year       HTML     39K 
                (Details)                                                        
55: R44         Significant Accounting Policies - Property and      HTML     45K 
                Equipment (Details)                                              
56: R45         Significant Accounting Policies - Pension Plans     HTML     37K 
                (Details)                                                        
57: R46         Discontinued Operations, Goodwill, and Intangible   HTML     49K 
                Assets - Sale of businesses (Details)                            
58: R47         Discontinued Operations, Goodwill, and Intangible   HTML     63K 
                Assets - Balance sheet (Details)                                 
59: R48         Discontinued Operations, Goodwill, and Intangible   HTML     73K 
                Assets - Income statement information (Details)                  
60: R49         Discontinued Operations, Goodwill, and Intangible   HTML     37K 
                Assets - Statement of cash flows (Details)                       
61: R50         Discontinued Operations, Goodwill, and Intangible   HTML     44K 
                Assets - Goodwill by segments (Details)                          
62: R51         Discontinued Operations, Goodwill, and Intangible   HTML     48K 
                Assets - Intangible assets (Details)                             
63: R52         Discontinued Operations, Goodwill, and Intangible   HTML     44K 
                Assets - Amortization expense (Details)                          
64: R53         Revenue Recognition (Details)                       HTML     35K 
65: R54         Revenue Recognition - Disaggregated revenues        HTML     51K 
                (Details)                                                        
66: R55         Revenue Recognition - Performance obligations       HTML     47K 
                (Details)                                                        
67: R56         Revenue Recognition - Accounts receivable, net      HTML     58K 
                (Details)                                                        
68: R57         Property and Equipment (Details)                    HTML     53K 
69: R58         Property and Equipment - Useful Lives (Details)     HTML     48K 
70: R59         Joint Ventures and Variable Interest Entities -     HTML    122K 
                Consolidated (Details)                                           
71: R60         Joint Ventures and Variable Interest Entities -     HTML    142K 
                Unconsolidated (Details)                                         
72: R61         Joint Ventures and Variable Interest Entities -     HTML     49K 
                Equity in Earnings (Details)                                     
73: R62         Pension Benefit Obligations - Benefit Obligation    HTML     64K 
                (Details)                                                        
74: R63         Pension Benefit Obligations - Asset Changes         HTML     60K 
                (Details)                                                        
75: R64         Pension Benefit Obligations - Funded Status         HTML     42K 
                (Details)                                                        
76: R65         Pension Benefit Obligations - Balance Sheet         HTML     51K 
                Recognition (Details)                                            
77: R66         Pension Benefit Obligations - Equity Recognition    HTML     45K 
                (Details)                                                        
78: R67         Pension Benefit Obligations - Periodic Cost         HTML     83K 
                (Details)                                                        
79: R68         Pension Benefit Obligations - AOCI (Details)        HTML     43K 
80: R69         Pension Benefit Obligations - Excess of Plan        HTML     49K 
                Assets (Details)                                                 
81: R70         Pension Benefit Obligations - Future payments       HTML     52K 
                (Details)                                                        
82: R71         Pension Benefit Obligations - Underlying            HTML     52K 
                assumptions (Details)                                            
83: R72         Pension Benefit Obligations - Target Allocation     HTML     57K 
                and Plan Assets Allocations (Details)                            
84: R73         Pension Benefit Obligations - Asset Categories      HTML     72K 
                (Details)                                                        
85: R74         Pension Benefit Obligations - Level 3 (Details)     HTML     47K 
86: R75         Pension Benefit Obligations - Multiemployer         HTML     36K 
                (Details)                                                        
87: R76         Debt - Long-term debt (Details)                     HTML     54K 
88: R77         Debt - Scheduled Maturities (Details)               HTML     49K 
89: R78         Debt - Credit Agreement (Details)                   HTML     80K 
90: R79         Debt - 2027 Senior Notes (Details)                  HTML     55K 
91: R80         Debt - Other Debt and Other Items (Details)         HTML     47K 
92: R81         Debt - Effective Interest Rate (Details)            HTML     38K 
93: R82         Derivative Financial Instruments and Fair Value     HTML     52K 
                Measurements - Cash Flow Hedges (Details)                        
94: R83         Derivative Financial Instruments and Fair Value     HTML     49K 
                Measurements - Fair Value Measurements (Details)                 
95: R84         Leases - Components of lease expense (Details)      HTML     54K 
96: R85         Leases - Additional balance sheet information       HTML     80K 
                (Details)                                                        
97: R86         Leases - Additional cash flow information           HTML     45K 
                (Details)                                                        
98: R87         Leases - Lease payments under operating lease       HTML     52K 
                (Details)                                                        
99: R88         Leases - Lease payments under finance lease         HTML     49K 
                (Details)                                                        
100: R89         Share-Based Payments - Defined Contribution Plan    HTML     35K  
                (Details)                                                        
101: R90         Share-Based Payments - Stock Incentive Plans        HTML     48K  
                (Details)                                                        
102: R91         Share-Based Payments - Restricted stock unit, PEP   HTML     97K  
                unit, and Stock Option activity (Details)                        
103: R92         Share-Based Payments - Options (Details)            HTML     47K  
104: R93         Share-Based Payments - PEP, RSU (Details)           HTML     52K  
105: R94         Income Taxes - Tax (Benefit) Expense (Details)      HTML     68K  
106: R95         Income Taxes - Federal Rate Reconciliation          HTML    115K  
                (Details)                                                        
107: R96         Income Taxes - Additional information (Details)     HTML     55K  
108: R97         Income Taxes - Deferred tax (Details)               HTML    118K  
109: R98         Income Taxes - Gross Unrecognized (Details)         HTML     55K  
110: R99         Earnings Per Share (Details)                        HTML     40K  
111: R100        Other Financial Information (Details)               HTML     71K  
112: R101        Reclassifications out of Accumulated Other          HTML     61K  
                Comprehensive Loss (Details)                                     
113: R102        Commitments and Contingencies - Commitments         HTML     49K  
                (Details)                                                        
114: R103        Commitments and Contingencies - DOE Project         HTML     59K  
                (Details)                                                        
115: R104        Commitments and Contingencies - Refinery            HTML     44K  
                Turnaround Project (Details)                                     
116: R105        Reportable Segments and Geographic Information -    HTML     88K  
                Summarized financial information (Details)                       
117: R106        Reportable Segments and Geographic Information -    HTML     42K  
                Geographic Information (Details)                                 
118: R107        Major Clients (Details)                             HTML     46K  
119: R108        Schedule II: Valuation and Qualifying Accounts      HTML     43K  
                (Details)                                                        
122: XML         IDEA XML File -- Filing Summary                      XML    233K  
120: XML         XBRL Instance -- acm-20230930x10k_htm                XML   5.28M  
121: EXCEL       IDEA Workbook of Financial Report Info              XLSX    224K  
 8: EX-101.CAL  XBRL Calculations -- acm-20230930_cal                XML    370K 
 9: EX-101.DEF  XBRL Definitions -- acm-20230930_def                 XML   1.14M 
10: EX-101.LAB  XBRL Labels -- acm-20230930_lab                      XML   2.22M 
11: EX-101.PRE  XBRL Presentations -- acm-20230930_pre               XML   1.67M 
 7: EX-101.SCH  XBRL Schema -- acm-20230930                          XSD    253K 
123: JSON        XBRL Instance as JSON Data -- MetaLinks              734±  1.14M  
124: ZIP         XBRL Zipped Folder -- 0001104659-23-118329-xbrl      Zip   1.29M

‘XML’   —   IDEA XML File — Filing Summary

This Document is an IDEA XML File.

                                                                                                                                                                                
<?xml version="1.0" encoding="windows-1252"?>
<FilingSummary>
<Version> 3.23.3 </Version>
<ProcessingTime/>
<ReportFormat> html </ReportFormat>
<ContextCount> 375 </ContextCount>
<ElementCount> 561 </ElementCount>
<EntityCount> 1 </EntityCount>
<FootnotesReported> false </FootnotesReported>
<SegmentCount> 113 </SegmentCount>
<ScenarioCount> 0 </ScenarioCount>
<TuplesReported> false </TuplesReported>
<UnitCount> 4 </UnitCount>
<MyReports>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R1.htm </HtmlFileName>
<LongName> 00090 - Document - Document and Entity Information </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DocumentDocumentAndEntityInformation </Role>
<ShortName> Document and Entity Information </ShortName>
<MenuCategory> Cover </MenuCategory>
<Position> 1 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R2.htm </HtmlFileName>
<LongName> 00100 - Statement - Consolidated Balance Sheets </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/StatementConsolidatedBalanceSheets </Role>
<ShortName> Consolidated Balance Sheets </ShortName>
<MenuCategory> Statements </MenuCategory>
<Position> 2 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R3.htm </HtmlFileName>
<LongName> 00105 - Statement - Consolidated Balance Sheets (Parenthetical) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/StatementConsolidatedBalanceSheetsParenthetical </Role>
<ShortName> Consolidated Balance Sheets (Parenthetical) </ShortName>
<MenuCategory> Statements </MenuCategory>
<Position> 3 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R4.htm </HtmlFileName>
<LongName> 00200 - Statement - Consolidated Statements of Operations </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/StatementConsolidatedStatementsOfOperations </Role>
<ShortName> Consolidated Statements of Operations </ShortName>
<MenuCategory> Statements </MenuCategory>
<Position> 4 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R5.htm </HtmlFileName>
<LongName> 00300 - Statement - Consolidated Statements of Comprehensive Income </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/StatementConsolidatedStatementsOfComprehensiveIncome </Role>
<ShortName> Consolidated Statements of Comprehensive Income </ShortName>
<MenuCategory> Statements </MenuCategory>
<Position> 5 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R6.htm </HtmlFileName>
<LongName> 00400 - Statement - Consolidated Statements of Stockholders' Equity </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/StatementConsolidatedStatementsOfStockholdersEquity </Role>
<ShortName> Consolidated Statements of Stockholders' Equity </ShortName>
<MenuCategory> Statements </MenuCategory>
<Position> 6 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R7.htm </HtmlFileName>
<LongName> 00500 - Statement - Consolidated Statements of Cash Flows </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/StatementConsolidatedStatementsOfCashFlows </Role>
<ShortName> Consolidated Statements of Cash Flows </ShortName>
<MenuCategory> Statements </MenuCategory>
<Position> 7 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R8.htm </HtmlFileName>
<LongName> 10101 - Disclosure - Significant Accounting Policies </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureSignificantAccountingPolicies </Role>
<ShortName> Significant Accounting Policies </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 8 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R9.htm </HtmlFileName>
<LongName> 10201 - Disclosure - New Accounting Pronouncements and Changes in Accounting </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureNewAccountingPronouncementsAndChangesInAccounting </Role>
<ShortName> New Accounting Pronouncements and Changes in Accounting </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 9 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R10.htm </HtmlFileName>
<LongName> 10301 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssets </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 10 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R11.htm </HtmlFileName>
<LongName> 10401 - Disclosure - Revenue Recognition </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureRevenueRecognition </Role>
<ShortName> Revenue Recognition </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 11 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R12.htm </HtmlFileName>
<LongName> 10501 - Disclosure - Property and Equipment </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePropertyAndEquipment </Role>
<ShortName> Property and Equipment </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 12 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R13.htm </HtmlFileName>
<LongName> 10601 - Disclosure - Joint Ventures and Variable Interest Entities </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureJointVenturesAndVariableInterestEntities </Role>
<ShortName> Joint Ventures and Variable Interest Entities </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 13 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R14.htm </HtmlFileName>
<LongName> 10701 - Disclosure - Pension Benefit Obligations </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligations </Role>
<ShortName> Pension Benefit Obligations </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 14 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R15.htm </HtmlFileName>
<LongName> 10801 - Disclosure - Debt </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebt </Role>
<ShortName> Debt </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 15 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R16.htm </HtmlFileName>
<LongName> 10901 - Disclosure - Derivative Financial Instruments and Fair Value Measurements </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDerivativeFinancialInstrumentsAndFairValueMeasurements </Role>
<ShortName> Derivative Financial Instruments and Fair Value Measurements </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 16 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R17.htm </HtmlFileName>
<LongName> 11001 - Disclosure - Concentration of Credit Risk </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureConcentrationOfCreditRisk </Role>
<ShortName> Concentration of Credit Risk </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 17 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R18.htm </HtmlFileName>
<LongName> 11101 - Disclosure - Leases </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeases </Role>
<ShortName> Leases </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 18 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R19.htm </HtmlFileName>
<LongName> 11201 - Disclosure - Stockholders' Equity </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureStockholdersEquity </Role>
<ShortName> Stockholders' Equity </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 19 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R20.htm </HtmlFileName>
<LongName> 11301 - Disclosure - Share-Based Payments </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureShareBasedPayments </Role>
<ShortName> Share-Based Payments </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 20 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R21.htm </HtmlFileName>
<LongName> 11401 - Disclosure - Income Taxes </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxes </Role>
<ShortName> Income Taxes </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 21 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R22.htm </HtmlFileName>
<LongName> 11501 - Disclosure - Earnings Per Share </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureEarningsPerShare </Role>
<ShortName> Earnings Per Share </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 22 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R23.htm </HtmlFileName>
<LongName> 11601 - Disclosure - Other Financial Information </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureOtherFinancialInformation </Role>
<ShortName> Other Financial Information </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 23 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R24.htm </HtmlFileName>
<LongName> 11701 - Disclosure - Reclassifications out of Accumulated Other Comprehensive Loss </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReclassificationsOutOfAccumulatedOtherComprehensiveLoss </Role>
<ShortName> Reclassifications out of Accumulated Other Comprehensive Loss </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 24 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R25.htm </HtmlFileName>
<LongName> 11801 - Disclosure - Commitments and Contingencies </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureCommitmentsAndContingencies </Role>
<ShortName> Commitments and Contingencies </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 25 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R26.htm </HtmlFileName>
<LongName> 11901 - Disclosure - Reportable Segments and Geographic Information </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReportableSegmentsAndGeographicInformation </Role>
<ShortName> Reportable Segments and Geographic Information </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 26 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R27.htm </HtmlFileName>
<LongName> 12001 - Disclosure - Major Clients </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureMajorClients </Role>
<ShortName> Major Clients </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 27 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R28.htm </HtmlFileName>
<LongName> 12101 - Disclosure - Schedule II: Valuation and Qualifying Accounts </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureScheduleIiValuationAndQualifyingAccounts </Role>
<ShortName> Schedule II: Valuation and Qualifying Accounts </ShortName>
<MenuCategory> Notes </MenuCategory>
<Position> 28 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R29.htm </HtmlFileName>
<LongName> 20102 - Disclosure - Significant Accounting Policies (Policies) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureSignificantAccountingPoliciesPolicies </Role>
<ShortName> Significant Accounting Policies (Policies) </ShortName>
<MenuCategory> Policies </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureSignificantAccountingPolicies </ParentRole>
<Position> 29 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R30.htm </HtmlFileName>
<LongName> 30303 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsTables </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssets </ParentRole>
<Position> 30 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R31.htm </HtmlFileName>
<LongName> 30403 - Disclosure - Revenue Recognition (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureRevenueRecognitionTables </Role>
<ShortName> Revenue Recognition (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureRevenueRecognition </ParentRole>
<Position> 31 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R32.htm </HtmlFileName>
<LongName> 30503 - Disclosure - Property and Equipment (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePropertyAndEquipmentTables </Role>
<ShortName> Property and Equipment (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosurePropertyAndEquipment </ParentRole>
<Position> 32 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R33.htm </HtmlFileName>
<LongName> 30603 - Disclosure - Joint Ventures and Variable Interest Entities (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureJointVenturesAndVariableInterestEntitiesTables </Role>
<ShortName> Joint Ventures and Variable Interest Entities (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureJointVenturesAndVariableInterestEntities </ParentRole>
<Position> 33 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R34.htm </HtmlFileName>
<LongName> 30703 - Disclosure - Pension Benefit Obligations (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsTables </Role>
<ShortName> Pension Benefit Obligations (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosurePensionBenefitObligations </ParentRole>
<Position> 34 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R35.htm </HtmlFileName>
<LongName> 30803 - Disclosure - Debt (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebtTables </Role>
<ShortName> Debt (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureDebt </ParentRole>
<Position> 35 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R36.htm </HtmlFileName>
<LongName> 30903 - Disclosure - Derivative Financial Instruments and Fair Value Measurements (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDerivativeFinancialInstrumentsAndFairValueMeasurementsTables </Role>
<ShortName> Derivative Financial Instruments and Fair Value Measurements (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureDerivativeFinancialInstrumentsAndFairValueMeasurements </ParentRole>
<Position> 36 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R37.htm </HtmlFileName>
<LongName> 31103 - Disclosure - Leases (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeasesTables </Role>
<ShortName> Leases (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureLeases </ParentRole>
<Position> 37 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R38.htm </HtmlFileName>
<LongName> 31403 - Disclosure - Income Taxes (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxesTables </Role>
<ShortName> Income Taxes (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureIncomeTaxes </ParentRole>
<Position> 38 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R39.htm </HtmlFileName>
<LongName> 31503 - Disclosure - Earnings Per Share (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureEarningsPerShareTables </Role>
<ShortName> Earnings Per Share (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureEarningsPerShare </ParentRole>
<Position> 39 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R40.htm </HtmlFileName>
<LongName> 31603 - Disclosure - Other Financial Information (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureOtherFinancialInformationTables </Role>
<ShortName> Other Financial Information (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureOtherFinancialInformation </ParentRole>
<Position> 40 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R41.htm </HtmlFileName>
<LongName> 31703 - Disclosure - Reclassifications out of Accumulated Other Comprehensive Loss (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReclassificationsOutOfAccumulatedOtherComprehensiveLossTables </Role>
<ShortName> Reclassifications out of Accumulated Other Comprehensive Loss (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureReclassificationsOutOfAccumulatedOtherComprehensiveLoss </ParentRole>
<Position> 41 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R42.htm </HtmlFileName>
<LongName> 31903 - Disclosure - Reportable Segments and Geographic Information (Tables) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReportableSegmentsAndGeographicInformationTables </Role>
<ShortName> Reportable Segments and Geographic Information (Tables) </ShortName>
<MenuCategory> Tables </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureReportableSegmentsAndGeographicInformation </ParentRole>
<Position> 42 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R43.htm </HtmlFileName>
<LongName> 40101 - Disclosure - Significant Accounting Policies - Fiscal Year (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureSignificantAccountingPoliciesFiscalYearDetails </Role>
<ShortName> Significant Accounting Policies - Fiscal Year (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 43 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R44.htm </HtmlFileName>
<LongName> 40102 - Disclosure - Significant Accounting Policies - Property and Equipment (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureSignificantAccountingPoliciesPropertyAndEquipmentDetails </Role>
<ShortName> Significant Accounting Policies - Property and Equipment (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 44 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R45.htm </HtmlFileName>
<LongName> 40103 - Disclosure - Significant Accounting Policies - Pension Plans (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureSignificantAccountingPoliciesPensionPlansDetails </Role>
<ShortName> Significant Accounting Policies - Pension Plans (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 45 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R46.htm </HtmlFileName>
<LongName> 40301 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Sale of businesses (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsSaleOfBusinessesDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Sale of businesses (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 46 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R47.htm </HtmlFileName>
<LongName> 40302 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Balance sheet (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsBalanceSheetDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Balance sheet (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 47 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R48.htm </HtmlFileName>
<LongName> 40303 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Income statement information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsIncomeStatementInformationDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Income statement information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 48 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R49.htm </HtmlFileName>
<LongName> 40304 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Statement of cash flows (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsStatementOfCashFlowsDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Statement of cash flows (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 49 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R50.htm </HtmlFileName>
<LongName> 40305 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Goodwill by segments (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsGoodwillBySegmentsDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Goodwill by segments (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 50 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R51.htm </HtmlFileName>
<LongName> 40306 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Intangible assets (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsIntangibleAssetsDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Intangible assets (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 51 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R52.htm </HtmlFileName>
<LongName> 40307 - Disclosure - Discontinued Operations, Goodwill, and Intangible Assets - Amortization expense (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDiscontinuedOperationsGoodwillAndIntangibleAssetsAmortizationExpenseDetails </Role>
<ShortName> Discontinued Operations, Goodwill, and Intangible Assets - Amortization expense (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 52 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R53.htm </HtmlFileName>
<LongName> 40401 - Disclosure - Revenue Recognition (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureRevenueRecognitionDetails </Role>
<ShortName> Revenue Recognition (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureRevenueRecognitionTables </ParentRole>
<Position> 53 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R54.htm </HtmlFileName>
<LongName> 40402 - Disclosure - Revenue Recognition - Disaggregated revenues (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureRevenueRecognitionDisaggregatedRevenuesDetails </Role>
<ShortName> Revenue Recognition - Disaggregated revenues (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 54 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R55.htm </HtmlFileName>
<LongName> 40403 - Disclosure - Revenue Recognition - Performance obligations (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureRevenueRecognitionPerformanceObligationsDetails </Role>
<ShortName> Revenue Recognition - Performance obligations (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 55 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R56.htm </HtmlFileName>
<LongName> 40404 - Disclosure - Revenue Recognition - Accounts receivable, net (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureRevenueRecognitionAccountsReceivableNetDetails </Role>
<ShortName> Revenue Recognition - Accounts receivable, net (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 56 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R57.htm </HtmlFileName>
<LongName> 40501 - Disclosure - Property and Equipment (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePropertyAndEquipmentDetails </Role>
<ShortName> Property and Equipment (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosurePropertyAndEquipmentTables </ParentRole>
<Position> 57 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R58.htm </HtmlFileName>
<LongName> 40502 - Disclosure - Property and Equipment - Useful Lives (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePropertyAndEquipmentUsefulLivesDetails </Role>
<ShortName> Property and Equipment - Useful Lives (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 58 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R59.htm </HtmlFileName>
<LongName> 40601 - Disclosure - Joint Ventures and Variable Interest Entities - Consolidated (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureJointVenturesAndVariableInterestEntitiesConsolidatedDetails </Role>
<ShortName> Joint Ventures and Variable Interest Entities - Consolidated (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 59 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R60.htm </HtmlFileName>
<LongName> 40602 - Disclosure - Joint Ventures and Variable Interest Entities - Unconsolidated (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureJointVenturesAndVariableInterestEntitiesUnconsolidatedDetails </Role>
<ShortName> Joint Ventures and Variable Interest Entities - Unconsolidated (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 60 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R61.htm </HtmlFileName>
<LongName> 40603 - Disclosure - Joint Ventures and Variable Interest Entities - Equity in Earnings (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureJointVenturesAndVariableInterestEntitiesEquityInEarningsDetails </Role>
<ShortName> Joint Ventures and Variable Interest Entities - Equity in Earnings (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 61 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R62.htm </HtmlFileName>
<LongName> 40701 - Disclosure - Pension Benefit Obligations - Benefit Obligation (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsBenefitObligationDetails </Role>
<ShortName> Pension Benefit Obligations - Benefit Obligation (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 62 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R63.htm </HtmlFileName>
<LongName> 40702 - Disclosure - Pension Benefit Obligations - Asset Changes (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsAssetChangesDetails </Role>
<ShortName> Pension Benefit Obligations - Asset Changes (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 63 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R64.htm </HtmlFileName>
<LongName> 40703 - Disclosure - Pension Benefit Obligations - Funded Status (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsFundedStatusDetails </Role>
<ShortName> Pension Benefit Obligations - Funded Status (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 64 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R65.htm </HtmlFileName>
<LongName> 40704 - Disclosure - Pension Benefit Obligations - Balance Sheet Recognition (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsBalanceSheetRecognitionDetails </Role>
<ShortName> Pension Benefit Obligations - Balance Sheet Recognition (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 65 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R66.htm </HtmlFileName>
<LongName> 40705 - Disclosure - Pension Benefit Obligations - Equity Recognition (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsEquityRecognitionDetails </Role>
<ShortName> Pension Benefit Obligations - Equity Recognition (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 66 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R67.htm </HtmlFileName>
<LongName> 40706 - Disclosure - Pension Benefit Obligations - Periodic Cost (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsPeriodicCostDetails </Role>
<ShortName> Pension Benefit Obligations - Periodic Cost (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 67 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R68.htm </HtmlFileName>
<LongName> 40707 - Disclosure - Pension Benefit Obligations - AOCI (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsAociDetails </Role>
<ShortName> Pension Benefit Obligations - AOCI (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 68 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R69.htm </HtmlFileName>
<LongName> 40708 - Disclosure - Pension Benefit Obligations - Excess of Plan Assets (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsExcessOfPlanAssetsDetails </Role>
<ShortName> Pension Benefit Obligations - Excess of Plan Assets (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 69 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R70.htm </HtmlFileName>
<LongName> 40709 - Disclosure - Pension Benefit Obligations - Future payments (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsFuturePaymentsDetails </Role>
<ShortName> Pension Benefit Obligations - Future payments (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 70 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R71.htm </HtmlFileName>
<LongName> 40710 - Disclosure - Pension Benefit Obligations - Underlying assumptions (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsUnderlyingAssumptionsDetails </Role>
<ShortName> Pension Benefit Obligations - Underlying assumptions (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 71 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R72.htm </HtmlFileName>
<LongName> 40711 - Disclosure - Pension Benefit Obligations - Target Allocation and Plan Assets Allocations (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsTargetAllocationAndPlanAssetsAllocationsDetails </Role>
<ShortName> Pension Benefit Obligations - Target Allocation and Plan Assets Allocations (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 72 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R73.htm </HtmlFileName>
<LongName> 40712 - Disclosure - Pension Benefit Obligations - Asset Categories (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsAssetCategoriesDetails </Role>
<ShortName> Pension Benefit Obligations - Asset Categories (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 73 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R74.htm </HtmlFileName>
<LongName> 40713 - Disclosure - Pension Benefit Obligations - Level 3 (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsLevel3Details </Role>
<ShortName> Pension Benefit Obligations - Level 3 (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 74 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R75.htm </HtmlFileName>
<LongName> 40714 - Disclosure - Pension Benefit Obligations - Multiemployer (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosurePensionBenefitObligationsMultiemployerDetails </Role>
<ShortName> Pension Benefit Obligations - Multiemployer (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 75 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R76.htm </HtmlFileName>
<LongName> 40801 - Disclosure - Debt - Long-term debt (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebtLongTermDebtDetails </Role>
<ShortName> Debt - Long-term debt (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 76 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R77.htm </HtmlFileName>
<LongName> 40802 - Disclosure - Debt - Scheduled Maturities (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebtScheduledMaturitiesDetails </Role>
<ShortName> Debt - Scheduled Maturities (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 77 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R78.htm </HtmlFileName>
<LongName> 40803 - Disclosure - Debt - Credit Agreement (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebtCreditAgreementDetails </Role>
<ShortName> Debt - Credit Agreement (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 78 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R79.htm </HtmlFileName>
<LongName> 40804 - Disclosure - Debt - 2027 Senior Notes (Details) </LongName>
<ReportType> Notes </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebt2027SeniorNotesDetails </Role>
<ShortName> Debt - 2027 Senior Notes (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 79 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R80.htm </HtmlFileName>
<LongName> 40805 - Disclosure - Debt - Other Debt and Other Items (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebtOtherDebtAndOtherItemsDetails </Role>
<ShortName> Debt - Other Debt and Other Items (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 80 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R81.htm </HtmlFileName>
<LongName> 40806 - Disclosure - Debt - Effective Interest Rate (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDebtEffectiveInterestRateDetails </Role>
<ShortName> Debt - Effective Interest Rate (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 81 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R82.htm </HtmlFileName>
<LongName> 40901 - Disclosure - Derivative Financial Instruments and Fair Value Measurements - Cash Flow Hedges (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDerivativeFinancialInstrumentsAndFairValueMeasurementsCashFlowHedgesDetails </Role>
<ShortName> Derivative Financial Instruments and Fair Value Measurements - Cash Flow Hedges (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 82 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R83.htm </HtmlFileName>
<LongName> 40902 - Disclosure - Derivative Financial Instruments and Fair Value Measurements - Fair Value Measurements (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureDerivativeFinancialInstrumentsAndFairValueMeasurementsFairValueMeasurementsDetails </Role>
<ShortName> Derivative Financial Instruments and Fair Value Measurements - Fair Value Measurements (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 83 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R84.htm </HtmlFileName>
<LongName> 41101 - Disclosure - Leases - Components of lease expense (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeasesComponentsOfLeaseExpenseDetails </Role>
<ShortName> Leases - Components of lease expense (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 84 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R85.htm </HtmlFileName>
<LongName> 41102 - Disclosure - Leases - Additional balance sheet information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeasesAdditionalBalanceSheetInformationDetails </Role>
<ShortName> Leases - Additional balance sheet information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 85 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R86.htm </HtmlFileName>
<LongName> 41103 - Disclosure - Leases - Additional cash flow information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeasesAdditionalCashFlowInformationDetails </Role>
<ShortName> Leases - Additional cash flow information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 86 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R87.htm </HtmlFileName>
<LongName> 41104 - Disclosure - Leases - Lease payments under operating lease (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeasesLeasePaymentsUnderOperatingLeaseDetails </Role>
<ShortName> Leases - Lease payments under operating lease (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 87 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R88.htm </HtmlFileName>
<LongName> 41105 - Disclosure - Leases - Lease payments under finance lease (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureLeasesLeasePaymentsUnderFinanceLeaseDetails </Role>
<ShortName> Leases - Lease payments under finance lease (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 88 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R89.htm </HtmlFileName>
<LongName> 41301 - Disclosure - Share-Based Payments - Defined Contribution Plan (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureShareBasedPaymentsDefinedContributionPlanDetails </Role>
<ShortName> Share-Based Payments - Defined Contribution Plan (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 89 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R90.htm </HtmlFileName>
<LongName> 41302 - Disclosure - Share-Based Payments - Stock Incentive Plans (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureShareBasedPaymentsStockIncentivePlansDetails </Role>
<ShortName> Share-Based Payments - Stock Incentive Plans (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 90 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R91.htm </HtmlFileName>
<LongName> 41303 - Disclosure - Share-Based Payments - Restricted stock unit, PEP unit, and Stock Option activity (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureShareBasedPaymentsRestrictedStockUnitPepUnitAndStockOptionActivityDetails </Role>
<ShortName> Share-Based Payments - Restricted stock unit, PEP unit, and Stock Option activity (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 91 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R92.htm </HtmlFileName>
<LongName> 41304 - Disclosure - Share-Based Payments - Options (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureShareBasedPaymentsOptionsDetails </Role>
<ShortName> Share-Based Payments - Options (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 92 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R93.htm </HtmlFileName>
<LongName> 41305 - Disclosure - Share-Based Payments - PEP, RSU (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureShareBasedPaymentsPepRsuDetails </Role>
<ShortName> Share-Based Payments - PEP, RSU (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 93 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R94.htm </HtmlFileName>
<LongName> 41401 - Disclosure - Income Taxes - Tax (Benefit) Expense (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxesTaxBenefitExpenseDetails </Role>
<ShortName> Income Taxes - Tax (Benefit) Expense (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 94 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R95.htm </HtmlFileName>
<LongName> 41402 - Disclosure - Income Taxes - Federal Rate Reconciliation (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxesFederalRateReconciliationDetails </Role>
<ShortName> Income Taxes - Federal Rate Reconciliation (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 95 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R96.htm </HtmlFileName>
<LongName> 41403 - Disclosure - Income Taxes - Additional information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxesAdditionalInformationDetails </Role>
<ShortName> Income Taxes - Additional information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 96 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R97.htm </HtmlFileName>
<LongName> 41404 - Disclosure - Income Taxes - Deferred tax (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxesDeferredTaxDetails </Role>
<ShortName> Income Taxes - Deferred tax (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 97 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R98.htm </HtmlFileName>
<LongName> 41405 - Disclosure - Income Taxes - Gross Unrecognized (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureIncomeTaxesGrossUnrecognizedDetails </Role>
<ShortName> Income Taxes - Gross Unrecognized (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 98 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R99.htm </HtmlFileName>
<LongName> 41501 - Disclosure - Earnings Per Share (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureEarningsPerShareDetails </Role>
<ShortName> Earnings Per Share (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureEarningsPerShareTables </ParentRole>
<Position> 99 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R100.htm </HtmlFileName>
<LongName> 41601 - Disclosure - Other Financial Information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureOtherFinancialInformationDetails </Role>
<ShortName> Other Financial Information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureOtherFinancialInformationTables </ParentRole>
<Position> 100 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R101.htm </HtmlFileName>
<LongName> 41701 - Disclosure - Reclassifications out of Accumulated Other Comprehensive Loss (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReclassificationsOutOfAccumulatedOtherComprehensiveLossDetails </Role>
<ShortName> Reclassifications out of Accumulated Other Comprehensive Loss (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureReclassificationsOutOfAccumulatedOtherComprehensiveLossTables </ParentRole>
<Position> 101 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R102.htm </HtmlFileName>
<LongName> 41801 - Disclosure - Commitments and Contingencies - Commitments (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureCommitmentsAndContingenciesCommitmentsDetails </Role>
<ShortName> Commitments and Contingencies - Commitments (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 102 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R103.htm </HtmlFileName>
<LongName> 41802 - Disclosure - Commitments and Contingencies - DOE Project (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureCommitmentsAndContingenciesDoeProjectDetails </Role>
<ShortName> Commitments and Contingencies - DOE Project (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 103 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R104.htm </HtmlFileName>
<LongName> 41803 - Disclosure - Commitments and Contingencies - Refinery Turnaround Project (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureCommitmentsAndContingenciesRefineryTurnaroundProjectDetails </Role>
<ShortName> Commitments and Contingencies - Refinery Turnaround Project (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 104 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R105.htm </HtmlFileName>
<LongName> 41901 - Disclosure - Reportable Segments and Geographic Information - Summarized financial information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReportableSegmentsAndGeographicInformationSummarizedFinancialInformationDetails </Role>
<ShortName> Reportable Segments and Geographic Information - Summarized financial information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 105 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R106.htm </HtmlFileName>
<LongName> 41902 - Disclosure - Reportable Segments and Geographic Information - Geographic Information (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureReportableSegmentsAndGeographicInformationGeographicInformationDetails </Role>
<ShortName> Reportable Segments and Geographic Information - Geographic Information (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<Position> 106 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R107.htm </HtmlFileName>
<LongName> 42001 - Disclosure - Major Clients (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureMajorClientsDetails </Role>
<ShortName> Major Clients (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureMajorClients </ParentRole>
<Position> 107 </Position>
</Report>
<Report instance="acm-20230930x10k.htm">
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<HtmlFileName> R108.htm </HtmlFileName>
<LongName> 42101 - Disclosure - Schedule II: Valuation and Qualifying Accounts (Details) </LongName>
<ReportType> Sheet </ReportType>
<Role> http://www.aecom.com/role/DisclosureScheduleIiValuationAndQualifyingAccountsDetails </Role>
<ShortName> Schedule II: Valuation and Qualifying Accounts (Details) </ShortName>
<MenuCategory> Details </MenuCategory>
<ParentRole> http://www.aecom.com/role/DisclosureScheduleIiValuationAndQualifyingAccounts </ParentRole>
<Position> 108 </Position>
</Report>
<Report>
<IsDefault> false </IsDefault>
<HasEmbeddedReports> false </HasEmbeddedReports>
<LongName> All Reports </LongName>
<ReportType> Book </ReportType>
<ShortName> All Reports </ShortName>
</Report>
</MyReports>
<InputFiles>
<File> acm-20230930.xsd </File>
<File> acm-20230930_cal.xml </File>
<File> acm-20230930_def.xml </File>
<File> acm-20230930_lab.xml </File>
<File> acm-20230930_pre.xml </File>
<File doctype="10-K" isDefinitelyFs="true" isUsgaap="true" original="acm-20230930x10k.htm"> acm-20230930x10k.htm </File>
</InputFiles>
<SupplementalFiles>
<File> acm-20230930x10k002.jpg </File>
<File> acm-20230930x10k003.jpg </File>
<File> acm-20230930x10k004.jpg </File>
<File> acm-20230930x10k005.jpg </File>
<File> acm-20230930x10k006.jpg </File>
<File> acm-20230930x10k007.jpg </File>
<File> acm-20230930x10k010.jpg </File>
</SupplementalFiles>
<BaseTaxonomies>
<BaseTaxonomy items="1"> http://fasb.org/srt/2023 </BaseTaxonomy>
<BaseTaxonomy items="1611"> http://fasb.org/us-gaap/2023 </BaseTaxonomy>
<BaseTaxonomy items="37"> http://xbrl.sec.gov/dei/2023 </BaseTaxonomy>
</BaseTaxonomies>
<HasPresentationLinkbase> true </HasPresentationLinkbase>
<HasCalculationLinkbase> true </HasCalculationLinkbase>
</FilingSummary>

40 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 8/09/23  AECOM                             10-Q        6/30/23   89:14M                                    Toppan Merrill/FA
 5/19/23  AECOM                             8-K:5,9     5/17/23   11:447K                                   Toppan Merrill/FA
 5/09/23  AECOM                             10-Q        3/31/23   86:12M                                    Toppan Merrill/FA
 2/07/23  AECOM                             10-Q       12/31/22   88:10M                                    Toppan Merrill/FA
 6/25/21  AECOM                             8-K:1,2,9   6/25/21   11:283K                                   Toppan Merrill/FA
 4/13/21  AECOM                             8-K:1,2,8,9 4/13/21   12:1.9M                                   Toppan Merrill/FA
 2/10/21  AECOM                             10-Q       12/31/20   90:12M                                    Toppan Merrill/FA
11/19/20  AECOM                             10-K        9/30/20  133:22M                                    Toppan Merrill/FA
 8/05/20  AECOM                             10-Q        6/30/20   91:12M                                    Toppan Merrill/FA
 5/06/20  AECOM                             10-Q        3/31/20   92:14M                                    Toppan Merrill/FA
 2/05/20  AECOM                             10-Q       12/31/19   98:15M                                    Toppan Merrill/FA
 2/03/20  AECOM                             8-K:1,2,7,9 1/28/20   14:1.2M                                   Toppan Merrill/FA
 1/23/20  AECOM                             DEF 14A     2/10/20    1:3.8M                                   Toppan Merrill-FA
 2/06/19  AECOM                             10-Q       12/28/18   86:13M                                    Toppan Merrill/FA
 1/23/19  AECOM                             DEF 14A     3/06/19    1:3.4M                                   Toppan Merrill-FA
11/13/18  AECOM                             10-K        9/28/18  128:28M                                    Toppan Merrill-FA
 3/14/18  AECOM                             8-K:1,2,7,9 3/13/18    4:2.3M                                   Toppan Merrill/FA
 2/07/18  AECOM                             10-Q       12/29/17   82:10M                                    Toppan Merrill/FA
 4/06/17  AECOM                             8-K:1,2,9   3/31/17    2:265K                                   Toppan Merrill/FA
 3/03/17  AECOM                             8-K:5,9     3/01/17    2:76K                                    Toppan Merrill/FA
 2/21/17  AECOM                             8-K:1,2,9   2/21/17    3:1.6M                                   Toppan Merrill/FA
 1/19/17  AECOM                             DEF 14A     3/01/17    1:2.8M                                   Toppan Merrill-FA
12/15/16  AECOM                             8-K:8,9    12/15/16    2:155K                                   Toppan Merrill/FA
 9/30/16  AECOM                             8-K:1,2,8,9 9/29/16    3:2M                                     Toppan Merrill/FA
 8/10/16  AECOM                             10-Q        7/01/16   74:13M                                    Toppan Merrill/FA
 5/11/16  AECOM                             10-Q        4/01/16   76:13M                                    Toppan Merrill/FA
 2/10/16  AECOM                             10-Q        1/01/16   72:10M                                    Toppan Merrill/FA
12/22/15  AECOM                             8-K:1,9    12/22/15    2:84K                                    Toppan Merrill/FA
 7/07/15  AECOM                             8-K:1,9     7/01/15    2:79K                                    Toppan Merrill/FA
 1/09/15  AECOM                             8-K:5,9     1/05/15    3:189K                                   Toppan Merrill/FA
11/17/14  AECOM                             10-K        9/30/14  103:26M                                    Toppan Merrill-FA
10/17/14  AECOM                             8-K:1,2,5,810/16/14    6:8.1M                                   Toppan Merrill/FA
 8/01/14  AECOM                             S-4                   10:3M                                     Toppan Merrill-FA
 3/12/14  AECOM                             8-K:5,9     3/06/14    3:152K                                   Toppan Merrill/FA
12/21/12  AECOM                             8-K:5,9    12/17/12    3:189K                                   Toppan Merrill/FA
11/21/11  AECOM                             10-K        9/30/11   92:14M                                    Toppan Merrill-FA
 1/21/11  AECOM                             DEF 14A     3/03/11    1:2.3M                                   Toppan Merrill-FA
 1/22/10  AECOM                             DEF 14A     3/05/10    1:2.1M                                   Toppan Merrill-FA
12/05/08  AECOM                             8-K:5,9    12/01/08    4:239K                                   Toppan Merrill/FA
 1/29/07  AECOM                             10-12G      1/26/07   49:13M                                    Toppan Merrill/FA
↑Top
Filing Submission 0001104659-23-118329   –   Alternative Formats (Word / Rich Text, HTML, Plain Text, et al.)
Copyright © 2024 Fran Finnegan & Company LLC – All Rights Reserved.
About — Privacy — Redactions — Help — Sat., May 11, 8:54:05.3am ET