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, 2019	Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes	$ 497	$ 105	$ 1,549		$ (402)
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	496	94	1,555		(422)
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	180	(54)	336		(216)
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	1	(8)	0		(10)
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	324	167	1,238		(172)
Other Income (Loss) [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes	(1)	0	(2)		0
Other Income (Loss) [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes	(4)	12	(14)		10
Other Income (Loss) [Member] | Other Contracts [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives held for other purposes	$ (3)	$ (12)	$ (9)	[1]	$ (14)	[1]

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