Intangible Assets and Goodwill - Fair Value of Intangible Assets and Related Accumulated Amortization Expense (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Finite-Lived Intangible Assets [Line Items]
Gross	$ 1,142	$ 1,036
Accumulated Amortization	(783)	(695)
Net	359	341
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets	24,706	27,323
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross	25,848	28,359
Net	25,065	27,664
Customer relationships and reacquired rights
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets	20,622	23,239
Visa trade name
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets	4,084	4,084
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross	836	726
Accumulated Amortization	(513)	(440)
Net	323	286
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross	195	199
Accumulated Amortization	(159)	(148)
Net	36	51
Reseller relationships
Finite-Lived Intangible Assets [Line Items]
Gross	95	95
Accumulated Amortization	(95)	(92)
Net	0	3
Other
Finite-Lived Intangible Assets [Line Items]
Gross	16	16
Accumulated Amortization	(16)	(15)
Net	$ 0	$ 1