v3.21.2
Debt - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Jul. 25, 2019
Aug. 31, 2020
Apr. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Debt Instrument [Line Items]            
Repayments of debt       $ 3,000,000,000 $ 0 $ 0
Commercial Paper Program            
Debt Instrument [Line Items]            
Aggregate principal       $ 3,000,000,000    
Debt term       397 days    
Commercial paper program, amount outstanding       $ 0 0  
Senior Notes | 2.20% Senior Notes due December 2020            
Debt Instrument [Line Items]            
Repayments of debt       $ 3,000,000,000    
Stated interest rate (percent)       2.20%    
Senior Notes | August 2020 Notes            
Debt Instrument [Line Items]            
Aggregate principal   $ 3,300,000,000        
Net aggregate proceeds   $ 3,200,000,000        
Senior Notes | August 2027 Notes            
Debt Instrument [Line Items]            
Debt term   7 years        
Stated interest rate (percent)       0.75%    
Senior Notes | August 2031 Notes            
Debt Instrument [Line Items]            
Debt term   10 years 6 months        
Stated interest rate (percent)       1.10%    
Senior Notes | August 2050 Notes            
Debt Instrument [Line Items]            
Debt term   30 years        
Stated interest rate (percent)       2.00%    
Senior Notes | April 2020 Notes            
Debt Instrument [Line Items]            
Aggregate principal     $ 4,000,000,000      
Net aggregate proceeds     $ 4,000,000,000      
Senior Notes | April 2027 Notes            
Debt Instrument [Line Items]            
Debt term     7 years      
Stated interest rate (percent)       1.90%    
Senior Notes | April 2030 Notes            
Debt Instrument [Line Items]            
Debt term     10 years      
Stated interest rate (percent)       2.05%    
Senior Notes | April 2040 Notes            
Debt Instrument [Line Items]            
Debt term     20 years      
Stated interest rate (percent)       2.70%    
Line of Credit | Credit Facility | Revolving Credit Facility            
Debt Instrument [Line Items]            
Debt term 5 years          
Maximum borrowing capacity $ 5,000,000,000          
Credit facility amount outstanding       $ 0 $ 0