Derivative Positions (Parenthetical) (Detail) (Not Designated as Hedging Instrument [Member], USD $) In Millions, unless otherwise specified									1 Months Ended
	Sep. 30, 2014 Trading Activity	Dec. 31, 2013 Trading Activity	Sep. 30, 2014 Derivative Financial Instruments, Assets Trading Activity	Dec. 31, 2013 Derivative Financial Instruments, Assets Trading Activity	Sep. 30, 2014 Derivative Financial Instruments, Liabilities [Member]	Dec. 31, 2013 Derivative Financial Instruments, Liabilities [Member]	Sep. 30, 2014 Derivative Financial Instruments, Liabilities [Member] Future [Member]	Dec. 31, 2013 Derivative Financial Instruments, Liabilities [Member] Future [Member]	May 31, 2009 Derivative Financial Instruments, Liabilities [Member] Visa Interest [Member]
Notional Amount Of Interest Rate Future Derivatives			$ 13,300	$ 15,200			$ 1,100	$ 885
Notional related to equity futures			409	157
Asset Amount Notional From Purchased And Written Interest Rate Swap Risk Participation Agreements	4	4
Notional Amount Liability Purchased And Written Interest Rate Swap Risk Participation Agreements	4	5
Number Of Shares Sold To Selected Financial Institutions									3.2
Notional Amount Derivative Liability Sale Of Shares					$ 55	$ 55