Guarantees - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	May. 31, 2009	Dec. 31, 2015	Dec. 31, 2014
Guarantee, Expiry Range of Tax Credits Sold, Minimum		3 years
Guarantee Period of Tax Credits Sold, Maximum		15 years
Business Combination, Contingent Consideration, Liability		$ 23	$ 27
Guarantee, Expiry Range of Tax Credits Sold, Maximum		7 years
Standby Letters of Credit
Maximum potential amount obligation		$ 2,900	3,000
Mortgage Servicing Rights [Member]
Loss Contingency Accrual, at Carrying Value		14	$ 25
Tax Credit Sales [Member]
Maximum potential amount obligation		$ 19
Derivative Financial Instruments, Liabilities [Member] | Visa Interest [Member]
Number Of Shares Sold To Selected Financial Institutions	3.2
Not Designated as Hedging Instrument [Member] | Derivative Financial Instruments, Liabilities [Member] | Visa Interest [Member]
Number Of Shares Sold To Selected Financial Institutions	3.2