v3.26.1
Legal Matters - Additional Information (Details) - USD ($)
$ in Millions
6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Loss Contingencies [Line Items]    
Deposits into the U.S. litigation escrow account $ 625 $ 375
Interchange Multidistrict Litigation    
Loss Contingencies [Line Items]    
Settlement percentage (in percent) 94.00%  
U.S. Covered Litigation    
Loss Contingencies [Line Items]    
Provision for legal matters $ 894 $ 1,019