Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Total		$ 3,792,188	$ 4,807,851
Interest rate contracts [Member]
Derivative [Line Items]
Total		2,302,421	3,051,548
Interest Rate Futures and Forwards [Member]
Derivative [Line Items]
Total		492,827	597,980
Interest Rate Swap [Member]
Derivative [Line Items]
Total		1,633,572	2,130,442
Interest Rate Options Written [Member]
Derivative [Line Items]
Total		85,733	158,861
Interest Rate Options Purchased [Member]
Derivative [Line Items]
Total		90,289	164,265
Foreign exchange contracts [Member]
Derivative [Line Items]
Total		1,260,009	1,520,980
Foreign Exchange Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		1,114,801	1,362,959
Foreign Exchange Options Written [Member]
Derivative [Line Items]
Total		31,766	44,876
Foreign Exchange Options Purchased [Member]
Derivative [Line Items]
Total		31,970	46,085
Foreign Exchange Spot [Member]
Derivative [Line Items]
Total		81,472	67,060
Commodities, equities and precious metals contracts [Member]
Derivative [Line Items]
Total		145,406	144,230
Commodities, Equities and Precious Metals, Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		65,008	55,678
Commodities, Equities and Precious Metals Options Written [Member]
Derivative [Line Items]
Total		35,138	39,035
Commodities, Equities and Precious Metals Options Purchased [Member]
Derivative [Line Items]
Total		45,260	49,517
Credit contracts [Member]
Derivative [Line Items]
Total		83,278	90,049
Other Contracts [Member]
Derivative [Line Items]
Total	[1]	$ 1,074	$ 1,044

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