v3.26.1
Joint Ventures and Variable Interest Entities - Schedule of Financial Information of Unconsolidated Joint Ventures Derived from Unaudited Financial Statements (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Sep. 30, 2025
Mar. 31, 2025
Sep. 30, 2024
Joint Ventures and Variable Interest Entities [Line Items]                
Current assets $ 6,349,916   $ 6,349,916     $ 6,730,227    
Total assets 12,026,900   12,026,900     12,200,249    
Current liabilities 6,009,650   6,009,650     5,928,816    
Total liabilities 9,627,495   9,627,495     9,504,065    
Joint ventures’ equity 2,399,405 $ 2,698,605 2,399,405 $ 2,698,605 $ 2,475,428 2,696,184 $ 2,466,287 $ 2,370,410
Total liabilities and owners’ equity 12,026,900   12,026,900     12,200,249    
AECOM’s investment in unconsolidated joint ventures 155,485   155,485     138,056    
Joint ventures summarized financial information                
Revenue 3,586,067 4,178,440 11,218,044 11,964,205        
Cost of revenue 3,620,109 3,851,490 10,674,596 11,078,090        
Gross profit (34,042) 326,950 543,448 886,115        
Net income (82,888) $ 159,737 200,912 498,481        
Equity Method Investment, Nonconsolidated Investee or Group of Investees                
Joint Ventures and Variable Interest Entities [Line Items]                
Current assets 1,625,300   1,625,300     1,537,700    
Non-current assets 666,700   666,700     708,000    
Total assets 2,292,000   2,292,000     2,245,700    
Current liabilities 1,138,000   1,138,000     1,107,800    
Non-current liabilities 130,300   130,300     92,400    
Total liabilities 1,268,300   1,268,300     1,200,200    
Joint ventures’ equity 1,023,700   1,023,700     1,045,500    
Total liabilities and owners’ equity 2,292,000   2,292,000     2,245,700    
AECOM’s investment in unconsolidated joint ventures $ 155,500   155,500     $ 138,100    
Joint ventures summarized financial information                
Revenue     2,076,500 2,108,100        
Cost of revenue     2,002,300 2,058,200        
Gross profit     74,200 49,900        
Net income     $ 49,900 $ 47,800