Revenues - Schedule of Net Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Net revenues	$ 7,059	$ 5,687
U.S.
Disaggregation of Revenue [Line Items]
Net revenues	3,178	2,667
International
Disaggregation of Revenue [Line Items]
Net revenues	3,881	3,020
Service revenues
Disaggregation of Revenue [Line Items]
Net revenues	3,193	2,677
Data processing revenues
Disaggregation of Revenue [Line Items]
Net revenues	3,614	3,033
International transaction revenues
Disaggregation of Revenue [Line Items]
Net revenues	2,174	1,451
Other revenues
Disaggregation of Revenue [Line Items]
Net revenues	449	384
Client incentives
Disaggregation of Revenue [Line Items]
Net revenues	$ (2,371)	$ (1,858)