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	Jun. 30, 2011
Line of Credit Facility [Line Items]
Commitments	$ 5,096
Financial Standby Letter of Credit | One Year from Balance Sheet Date
Line of Credit Facility [Line Items]
Commitments	2,079	[1]
Financial Standby Letter of Credit | One Year from Balance Sheet Date | Commercial
Line of Credit Facility [Line Items]
Commitments	77
Financial Standby Letter of Credit | More than One and within Five Years from Balance Sheet Date
Line of Credit Facility [Line Items]
Commitments	2,843	[1]
Financial Standby Letter of Credit | More than One and within Five Years from Balance Sheet Date | Commercial
Line of Credit Facility [Line Items]
Commitments	$ 11

[1] Includes $77 and $11 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.