v3.26.1
Fair Value Measurements - Fair Value of Long-Term Debt (Details) - USD ($)
$ in Billions
Mar. 31, 2026
Sep. 30, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt $ 8.2 $ 8.9
Public debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt 7.7 8.4
Other long-term debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of long term debt $ 0.5 $ 0.5