Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Total		$ 4,613,258	$ 4,807,851
Interest rate contracts [Member]
Derivative [Line Items]
Total		2,941,572	3,051,548
Interest Rate Futures and Forwards [Member]
Derivative [Line Items]
Total		765,243	597,980
Interest Rate Swap [Member]
Derivative [Line Items]
Total		1,938,082	2,130,442
Interest Rate Options Written [Member]
Derivative [Line Items]
Total		116,380	158,861
Interest Rate Options Purchased [Member]
Derivative [Line Items]
Total		121,867	164,265
Foreign exchange contracts [Member]
Derivative [Line Items]
Total		1,420,633	1,520,980
Foreign Exchange Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		1,304,885	1,362,959
Foreign Exchange Options Written [Member]
Derivative [Line Items]
Total		35,269	44,876
Foreign Exchange Options Purchased [Member]
Derivative [Line Items]
Total		36,088	46,085
Foreign Exchange Spot [Member]
Derivative [Line Items]
Total		44,391	67,060
Commodities, equities and precious metals contracts [Member]
Derivative [Line Items]
Total		154,794	144,230
Commodities, Equities and Precious Metals, Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		73,740	55,678
Commodities, Equities and Precious Metals Options Written [Member]
Derivative [Line Items]
Total		35,418	39,035
Commodities, Equities and Precious Metals Options Purchased [Member]
Derivative [Line Items]
Total		45,636	49,517
Credit contracts [Member]
Derivative [Line Items]
Total		95,364	90,049
Other Contracts [Member]
Derivative [Line Items]
Total	[1]	$ 895	$ 1,044

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