Accrued Litigation for Both Covered and Non-Covered Litigation (Detail) $ in Millions	3 Months Ended		16 Months Ended
	Dec. 31, 2018 USD ($) merchant	Dec. 31, 2017 USD ($)	Jan. 31, 2019 USD ($) merchant	Dec. 04, 2018
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	$ 1,434	$ 982	$ 982
Provision for legal matters	90	0
Balance at end of period	$ 1,489	830
Interchange Rate, Card-Not-Present, Credit				0.015
Interchange Rate, Card-Not-Present, Debit				0.0115
Interchange Rate, Card Present, Credit				0.003
Interchange Rate, Card Present, Debit				0.002
U.K. Merchant Litigation
Loss Contingencies [Line Items]
Number of plaintiffs | merchant	450
Unsettled
Loss Contingency Accrual [Roll Forward]
Provision for legal matters	$ 7	0
Settled Litigation
Loss Contingency Accrual [Roll Forward]
Loss Contingency Accrual, Payments	$ (42)	(152)
Threatened Litigation | U.K. Merchant Litigation
Loss Contingencies [Line Items]
Number of plaintiffs | merchant	30
U.S. Covered Litigation
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	$ 1,428	978	978
Balance at end of period	1,428	828
U.S. Covered Litigation | Settled Litigation
Loss Contingency Accrual [Roll Forward]
Loss Contingency Accrual, Payments	0	(150)
VE Territory Covered Litigation
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	0	1	$ 1
Provision for legal matters	90	0
Balance at end of period	55	0
VE Territory Covered Litigation | Settled Litigation
Loss Contingency Accrual [Roll Forward]
Loss Contingency Accrual, Payments	$ (35)	$ (1)
Subsequent Event | U.K. Merchant Litigation
Loss Contingencies [Line Items]
Number of claims settled | merchant			75
Merchants with outstanding claims | merchant			350