Revenues - Schedule of Net Revenues (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Net revenues	$ 7,275	$ 6,130	$ 21,523	$ 17,546
U.S.
Disaggregation of Revenue [Line Items]
Net revenues	3,170	2,806	9,427	8,156
International
Disaggregation of Revenue [Line Items]
Net revenues	4,105	3,324	12,096	9,390
Service revenues
Disaggregation of Revenue [Line Items]
Net revenues	3,189	2,828	9,903	8,350
Data processing revenues
Disaggregation of Revenue [Line Items]
Net revenues	3,579	3,327	10,673	9,356
International transaction revenues
Disaggregation of Revenue [Line Items]
Net revenues	2,560	1,696	6,942	4,635
Other revenues
Disaggregation of Revenue [Line Items]
Net revenues	517	409	1,440	1,185
Client incentives
Disaggregation of Revenue [Line Items]
Net revenues	$ (2,570)	$ (2,130)	$ (7,435)	$ (5,980)