v3.26.1
Fair Value Measurements - Schedule of Carrying Amounts and Estimated Fair Values of Long-term Debt (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2025
Carrying amount      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Long-term debt $ 6,768 $ 6,701 $ 6,644
Estimated fair value      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Long-term debt $ 6,880 $ 6,777 $ 6,743