v3.26.1
Commitments and Contingencies (Details)
$ in Millions
9 Months Ended
Jun. 30, 2026
USD ($)
project
Sep. 30, 2025
USD ($)
Jun. 30, 2025
USD ($)
Commitments and Contingencies [Line Items]      
Accrued contract costs $ 1,437.7 $ 1,419.0  
Number of business projects | project 2    
Fund Investment Capital      
Commitments and Contingencies [Line Items]      
Capital commitments $ 3.7    
Commitment period (in years) 2 years    
Standby Letters of Credit      
Commitments and Contingencies [Line Items]      
Outstanding standby letters of credit $ 906.9 899.4  
Amount available under unsecured credit facilities 411.8    
Contingently liable for issuance of standby letters of credit and surety bonds 911.3    
Corporate guarantees 403.9    
Surety Bond      
Commitments and Contingencies [Line Items]      
Contingently liable for issuance of standby letters of credit and surety bonds 6,400.0    
Damages sought 1,000.0    
Professional Liability Accrual      
Commitments and Contingencies [Line Items]      
Accrued contract costs 881.9 $ 893.7  
Insurance receivable for malpractice $ 389.9   $ 418.4