v3.26.3
Basis of Presentation and Accounting Policies - Legacy Asbestos and Environmental Matters (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2024
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Other income (expense) $ 50 $ (126) $ 62
Net income (loss) $ 1,407 $ 749 $ 948
Basic (in dollars per share) $ 12.60 $ 7.69 $ 8.32
Change in Accounting Method Accounted for as Change in Estimate      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]      
Other liabilities   $ 441  
Receivables, current and other assets, noncurrent   151  
Other income (expense)   (136)  
Net income (loss)   $ (103)  
Basic (in dollars per share)   $ (0.91)  
Change in accounting method, expense   $ 91  
Loss contingency, accrual, current   $ 45