XML 19 R1.htm IDEA: XBRL DOCUMENT v3.23.3
Document and Entity Information - USD ($)
$ in Billions
 12 Months Ended
Sep. 30, 2023
Nov. 10, 2023
Document and Entity Information    
Document Type 10-K  
Document Period End Date Sep. 30, 2023  
Document Annual Report true  
Document Transition Report false  
Entity File Number 000-52423  
Entity Registrant Name AECOM  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 61-1088522  
Entity Address, Address Line One 13355 Noel Road  
Entity Address, City or Town Dallas  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 75240  
City Area Code 972  
Local Phone Number 788-1000  
Title of 12(b) Security Common Stock, $0.01 par value  
Trading Symbol ACM  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   135,987,254
Entity Well-known Seasoned Issuer Yes  
Entity Voluntary Filers No  
Entity Public Float $ 11.7  
Document Financial Statement Error Correction [Flag] false  
Entity Central Index Key 0000868857  
Current Fiscal Year End Date --09-30  
Document Fiscal Year Focus 2023  
Document Fiscal Period Focus FY  
Amendment Flag false  
ICFR Auditor Attestation Flag true  
Auditor Name Ernst & Young LLP  
Auditor Firm ID 42  
Auditor Location Los Angeles, California