v3.26.1
Commitments and Contingencies - Legal Claims and Insurance (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Sep. 30, 2025
Rollforward of reserves for legal claims          
Reserves for legal claims, beginning of period $ 1,122.8 $ 939.1 $ 1,143.6 $ 949.6  
Increase in reserves 27.0 66.7 50.3 72.5  
Payments (13.1) (14.5) (57.2) (30.8)  
Reserves for legal claims, end of period $ 1,136.7 991.3 $ 1,136.7 991.3  
Construction Defect Portion of Loss Contingency Accrual 99.00%   99.00%   98.00%
Litigation Settlement, Expense     $ 58.0 97.3  
Insurance receivables $ 152.3 $ 126.7 $ 152.3 $ 126.7 $ 167.0