Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Total		$ 4,807,851	$ 5,556,668
Interest rate contracts [Member]
Derivative [Line Items]
Total		3,051,548	4,203,667
Interest Rate Futures and Forwards [Member]
Derivative [Line Items]
Total		597,980	787,049
Interest Rate Swap [Member]
Derivative [Line Items]
Total		2,130,442	3,203,048
Interest Rate Options Written [Member]
Derivative [Line Items]
Total		158,861	106,009
Interest Rate Options Purchased [Member]
Derivative [Line Items]
Total		164,265	107,561
Foreign exchange contracts [Member]
Derivative [Line Items]
Total		1,520,980	1,144,808
Foreign Exchange Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		1,362,959	1,052,088
Foreign Exchange Options Written [Member]
Derivative [Line Items]
Total		44,876	30,567
Foreign Exchange Options Purchased [Member]
Derivative [Line Items]
Total		46,085	31,069
Foreign Exchange Spot [Member]
Derivative [Line Items]
Total		67,060	31,084
Commodities, equities and precious metals contracts [Member]
Derivative [Line Items]
Total		144,230	110,159
Commodities, Equities and Precious Metals, Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		55,678	41,328
Commodities, Equities and Precious Metals Options Written [Member]
Derivative [Line Items]
Total		39,035	28,595
Commodities, Equities and Precious Metals Options Purchased [Member]
Derivative [Line Items]
Total		49,517	40,236
Credit contracts [Member]
Derivative [Line Items]
Total		90,049	97,298
Other Contracts [Member]
Derivative [Line Items]
Total	[1]	$ 1,044	$ 736

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