Accrued Litigation for Both Covered and Non-Covered Litigation (Detail) $ in Millions		9 Months Ended
	Feb. 17, 2017 case_filed	Jun. 30, 2017 USD ($) merchant	Jun. 30, 2016 USD ($)	Apr. 20, 2017	Nov. 30, 2016 plaintiff_class
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period		$ 981	$ 1,024
Balance at end of period		$ 995	978
Case filed in Texas state court | case_filed	1
U.K. Merchant Litigation
Loss Contingency Accrual [Roll Forward]
Number of plaintiffs | merchant		200
Number of claims settled | merchant		19
Merchants with outstanding claims | merchant		175
Number of claims settled during trial | merchant		15
Loss Contingency, Claims Settled after Trial, Number | merchant		4
Number of claims pending trial decision | merchant		1
Threatened Litigation | U.K. Merchant Litigation
Loss Contingency Accrual [Roll Forward]
Number of plaintiffs | merchant		30
Unsettled
Loss Contingency Accrual [Roll Forward]
Provision for legal matters		$ 17	1
Settled Litigation
Loss Contingency Accrual [Roll Forward]
Payments on litigation matters		(145)	(47)
U.S. Covered Litigation
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period		978	1,023
Balance at end of period		978	978
U.S. Covered Litigation | Settled Litigation
Loss Contingency Accrual [Roll Forward]
Payments on litigation matters		0	(45)
VE Territory Covered Litigation
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period		2
Provision for legal matters		142	$ 0
Balance at end of period		0
VE Territory Covered Litigation | Settled Litigation
Loss Contingency Accrual [Roll Forward]
Payments on litigation matters		$ (144)
Interchange Multidistrict Litigation
Loss Contingency Accrual [Roll Forward]
Number of putative classes of plaintiffs | plaintiff_class					2
Merchants with settlement agreements (percent)				34.00%