Derivative Positions (Additional Information) (Detail) - USD ($) shares in Millions, $ in Millions		1 Months Ended
		May. 31, 2009	Sep. 30, 2015		Dec. 31, 2014
Derivative Asset, Notional Amount			$ 140,073		$ 118,139
Derivative Liability, Notional Amount			109,543		114,144
Other Trading [Member] | Credit Risk Contract [Member]
Derivative Asset, Notional Amount			6		4
Derivative Liability, Notional Amount			9	[1],[2]	4
Derivative Financial Instruments, Liabilities [Member] | Visa Interest [Member]
Number Of Shares Sold To Selected Financial Institutions		3
Visa Interest [Member] | Loans [Member] | Other Contract [Member]
Derivative Liability, Notional Amount			49	[1],[2]	49
Interest rate futures [Member] | Loans [Member] | Interest Rate Contract [Member]
Derivative Asset, Notional Amount	[1],[2]		848
Derivative Liability, Notional Amount	[1],[2]				791
Interest rate futures [Member] | Other Trading [Member] | Interest Rate Contract [Member]
Derivative Asset, Notional Amount			12,700		10,300
Equity futures [Member] | Other Trading [Member] | Equity Contract [Member]
Derivative Asset, Notional Amount			$ 536		$ 563

[1] Amount includes $791 million of notional amounts related to interest rate futures. These futures contracts settle in cash daily, one day in arrears. The derivative asset or liability associated with the one day lag is included in the fair value column of this table.

[2] See “Economic Hedging and Trading Activities” in this Note for further discussion.