Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Other Purpose (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes		$ 227	$ 171	$ 567	$ 336
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes		213	184	570	345
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes		72	111	75	325
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes		(6)	8	3	20
Gain (Loss) on Instruments Designated at Fair Value and Related Derivatives [Member] | Equity contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes		161	81	521	32
Other Income [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes		2	(29)	(30)	(41)
Other Income [Member] | Other Contract [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes	[1]	$ (2)	$ 0	$ (2)	$ 0

[1] Consists of swap agreements entered into in conjunction with the sales of certain Visa Class B Shares.