Legal Matters - Additional Information (Detail) $ in Millions					1 Months Ended	2 Months Ended	12 Months Ended			52 Months Ended	136 Months Ended	137 Months Ended
	May 29, 2020 state	Dec. 13, 2019 USD ($)	Sep. 17, 2018 USD ($)	Jun. 30, 2016 litigation_case	Oct. 31, 2011 financial_institution non-bankATMOperator	Jun. 16, 2021 complaint state	Sep. 30, 2024 USD ($) plaintiff	Sep. 30, 2023 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2024 USD ($) complaint plaintiff	Nov. 13, 2024 merchant	Sep. 30, 2024 USD ($) case_filed plaintiff	Oct. 01, 2024 lawsuit	Jul. 31, 2024 class_action_case	Sep. 30, 2022 USD ($)	Jun. 01, 2022 class_action_case
Loss Contingencies [Line Items]
Loss contingency accrual							$ 1,727	$ 1,751		$ 1,727		$ 1,727			$ 1,456
Number of complaints filed | complaint										3
Number of states | state	24					25
Number of separate complaints filed | complaint						2
Number of plaintiff appealed | plaintiff							3			3		3
Number of class action lawsuits | class_action_case														3		2
Subsequent Event
Loss Contingencies [Line Items]
Number of class action lawsuits | lawsuit													1
Visa, MasterCard, and Certain U.S. Financial Institutions
Loss Contingencies [Line Items]
Loss contingency accrual			$ 5,300
Possible return to defendants		$ 700
U.S. Covered Litigation
Loss Contingencies [Line Items]
Provision for unsettled legal matters							$ 140	906
Period of accrual			5 years
Company's share of an additional settlement payment							224	726
Loss contingency accrual							$ 1,537	$ 1,621		$ 1,537		$ 1,537			$ 1,441
Possible return to defendants		$ 467
Settled Litigation | U.S. Covered Litigation
Loss Contingencies [Line Items]
Company's share of an additional settlement payment			$ 600
Class Plaintiffs
Loss Contingencies [Line Items]
Payments for legal settlements									$ 4,000
Settlement, further distribution of default interchange									$ 500
Loss contingency, further distributions, default period									8 months
Loss contingency, number of cases appointed counsel | litigation_case				2
Interchange Multidistrict Litigation
Loss Contingencies [Line Items]
Settlement percentage							73.00%			73.00%		73.00%
Interchange Multidistrict Litigation | U.S. Covered Litigation | Visa, MasterCard, and Certain U.S. Financial Institutions
Loss Contingencies [Line Items]
Provision for unsettled legal matters			$ 900
Interchange Multidistrict Litigation | U.S. Covered Litigation
Loss Contingencies [Line Items]
Provision for unsettled legal matters									$ 1,100
Interchange Opt Out Litigation
Loss Contingencies [Line Items]
Number of cases | case_filed												50
Europe Merchant Litigation | Subsequent Event
Loss Contingencies [Line Items]
Number of plaintiffs | merchant											1,150
Number of claims settled | merchant											475
Number of claims pending | merchant											600
Europe Merchant Litigation | Threatened Litigation | Subsequent Event
Loss Contingencies [Line Items]
Number of plaintiffs | merchant											30
National ATM Council Class Action
Loss Contingencies [Line Items]
Number of non-bank ATM operators | non-bankATMOperator					13
Consumer Class Actions
Loss Contingencies [Line Items]
Number of claims pending | financial_institution					2
U.S. Debit Class Actions | Subsequent Event
Loss Contingencies [Line Items]
Number of class action lawsuits | lawsuit													5
Mackim v. Visa Inc.
Loss Contingencies [Line Items]
Number of financial institutions | financial_institution					3