Standby and Commercial Letters of Credit, Conditional Commitments Issued to Guarantee the Performance of a Customer to a Third Party (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Line of Credit Facility [Line Items]
Commitments Fair Value Disclosure	$ 62,050		$ 53,403
Financial Standby Letter of Credit
Line of Credit Facility [Line Items]
Commitments Fair Value Disclosure	4,129
Financial Standby Letter of Credit | More than One and within Five Years from Balance Sheet Date
Line of Credit Facility [Line Items]
Commitments Fair Value Disclosure	2,173	[1]
Financial Standby Letter of Credit | Commercial [Member] | One Year From Balance Sheet Date
Line of Credit Facility [Line Items]
Commitments Fair Value Disclosure	121
Financial Standby Letter of Credit | Commercial [Member] | More than One and within Five Years from Balance Sheet Date
Line of Credit Facility [Line Items]
Commitments Fair Value Disclosure	$ 4

[1] Includes $121 and $4 issued on behalf of commercial customers to facilitate trade payments in U.S. dollars and foreign currencies which expire less than one year and between one and five years, respectively.