v3.20.2
Debt - Narrative (Details) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
Apr. 30, 2020
Jun. 30, 2020
Jun. 30, 2020
Jun. 30, 2019
Sep. 30, 2019
Debt Instrument [Line Items]          
Commercial paper program, outstanding obligations   $ 0 $ 0   $ 0
Proceeds from issuance of senior notes (Note 8)     3,985,000,000 $ 0  
Commercial Paper          
Debt Instrument [Line Items]          
Commercial paper program, amount available   3,000,000,000.0 $ 3,000,000,000.0    
Credit agreement term     397 days    
Repayments of commercial paper   $ 1,000,000,000.0      
Senior Notes | 2020 Notes          
Debt Instrument [Line Items]          
Proceeds from issuance of senior notes (Note 8) $ 4,000,000,000.0        
Stated interest rate (percent)   2.20% 2.20%    
Senior Notes | 1.90% Senior Notes due April 2027          
Debt Instrument [Line Items]          
Stated interest rate (percent) 1.90% 1.90% 1.90%    
Senior Notes | 2030 Notes          
Debt Instrument [Line Items]          
Stated interest rate (percent) 2.05%        
Senior Notes | 2040 Notes          
Debt Instrument [Line Items]          
Stated interest rate (percent) 2.70%        
Senior Notes | Minimum | 2020 Notes          
Debt Instrument [Line Items]          
Credit agreement term 7 years        
Senior Notes | Maximum | 2020 Notes          
Debt Instrument [Line Items]          
Credit agreement term 20 years