v3.25.3
Income Taxes - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Sep. 30, 2022
Tax Credit Carryforward [Line Items]        
US income before taxes $ 14,776 $ 14,537 $ 13,339  
Deferred tax assets, net $ 1,528 $ 1,641    
Effective income tax rate (in percent) 17.00% 17.00% 18.00%  
Recognized tax benefit $ 263 $ 223 $ 142  
Income taxes receivable included in prepaid and other current assets 232 832    
Income taxes payable included in accrued taxes as part of accrued liabilities 512 577    
Accrued income taxes included in other long-term liabilities 309 1,400    
Decreased Singapore tax as a result of the tax incentive agreement $ 453 $ 419 $ 468  
Benefit of the tax incentive agreement on diluted net income per share (in dollars per share) $ 0.23 $ 0.21 $ 0.22  
Total unrecognized tax benefits exclusive of interest and penalties $ 1,672 $ 3,750 $ 3,497 $ 2,683
Unrecognized tax benefits, if recognized, would reduce the effective tax rate in a future period 1,500 1,400 1,600  
Interest expense included in interest expense and administrative and other 140 29 34  
Accrued interest related to uncertain tax positions in other long term liabilities 160 300    
Foreign Country        
Tax Credit Carryforward [Line Items]        
Net operating loss carryforwards 1,100      
Other Assets        
Tax Credit Carryforward [Line Items]        
Deferred tax assets, net 128 140    
Non-current income tax receivable 427 442    
Non United States Customers        
Tax Credit Carryforward [Line Items]        
US income before taxes $ 6,000 $ 5,100 $ 4,200