Derivative Positions (Additional Information) (Detail) - USD ($) shares in Millions, $ in Millions	1 Months Ended
	May 31, 2009	Mar. 31, 2017	Dec. 31, 2016
Derivative Asset, Notional Amount		$ 119,513	$ 133,395
Derivative Liability, Notional Amount		153,545	153,160
Credit Risk Contract [Member]
Derivative Asset, Notional Amount		4	5
Derivative Liability, Notional Amount		12	13
Derivative Financial Instruments, Liabilities [Member] | Visa Interest [Member]
Number Of Shares Sold To Selected Financial Institutions	3.2
Visa Interest [Member] | Other Contract [Member]
Derivative Liability, Notional Amount		49	49
Interest rate futures [Member] | Mortgage Servicing Rights [Member]
Derivative Liability, Notional Amount		7,900	6,700
Interest rate futures [Member] | Loans Held For Sale [Member]
Derivative Asset, Notional Amount		913	720
Interest rate futures [Member] | Other Trading [Member]
Derivative Asset, Notional Amount		11,600	12,300
Equity futures [Member] | Equity Contract [Member]
Derivative Asset, Notional Amount		$ 710	$ 629