Accrued Litigation for Both Covered and Non-Covered Litigation (Detail) $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2017 merchant	Dec. 31, 2017 USD ($) merchant	Dec. 31, 2016 USD ($)	Apr. 20, 2017
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period		$ 982	$ 981
Balance at end of period		$ 830	994
U.K. Merchant Litigation
Loss Contingency Accrual [Roll Forward]
Number of plaintiffs | merchant		300
Number of claims settled | merchant		75
Merchants with outstanding claims | merchant		200
Number of merchant claims not settled before trial | 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		$ 0	15
Settled Litigation
Loss Contingency Accrual [Roll Forward]
Payments on litigation matters		(152)	(88)
U.S. Covered Litigation
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period		978	978
Balance at end of period		828	978
U.S. Covered Litigation | Settled Litigation
Loss Contingency Accrual [Roll Forward]
Payments on litigation matters		(150)	0
VE Territory Covered Litigation
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period		1	2
Provision for legal matters		0	86
Balance at end of period		0	0
VE Territory Covered Litigation | Settled Litigation
Loss Contingency Accrual [Roll Forward]
Payments on litigation matters		$ (1)	$ (88)
Interchange Multidistrict Litigation
Loss Contingency Accrual [Roll Forward]
Merchants with settlement agreements (percent)				51.00%