Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Total		$ 4,135,130	$ 4,212,040
Interest rate contracts [Member]
Derivative [Line Items]
Total		2,805,579	2,748,778
Interest Rate Futures and Forwards [Member]
Derivative [Line Items]
Total		501,635	149,413
Interest Rate Swap [Member]
Derivative [Line Items]
Total		2,142,183	2,453,526
Interest Rate Options Written [Member]
Derivative [Line Items]
Total		74,741	65,747
Interest Rate Options Purchased [Member]
Derivative [Line Items]
Total		87,020	80,092
Foreign exchange contracts [Member]
Derivative [Line Items]
Total		1,105,971	1,186,671
Foreign Exchange Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		965,301	980,811
Foreign Exchange Options Written [Member]
Derivative [Line Items]
Total		52,845	81,132
Foreign Exchange Options Purchased [Member]
Derivative [Line Items]
Total		53,260	82,004
Foreign Exchange Spot [Member]
Derivative [Line Items]
Total		34,565	42,724
Commodities, equities and precious metals contracts [Member]
Derivative [Line Items]
Total		99,682	88,521
Commodities, Equities and Precious Metals, Swaps, Futures and Forwards [Member]
Derivative [Line Items]
Total		49,555	35,546
Commodities, Equities and Precious Metals Options Written [Member]
Derivative [Line Items]
Total		19,495	19,601
Commodities, Equities and Precious Metals Options Purchased [Member]
Derivative [Line Items]
Total		30,632	33,374
Credit contracts [Member]
Derivative [Line Items]
Total		123,714	188,070
Other Contract [Member]
Derivative [Line Items]
Total	[1]	$ 184	$ 0

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