Risk Ratings of the Notional Amount of Risk Participation Agreements (Detail) (Interest Rate Contract, USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Notional amount of the risk participation agreements	$ 1,233	$ 1,203
Lender Concentration Risk \| Pass
Notional amount of the risk participation agreements	1,194	1,153
Lender Concentration Risk \| Risk Level, Special Mention
Notional amount of the risk participation agreements	2	38
Lender Concentration Risk \| Risk Level, Substandard
Notional amount of the risk participation agreements	$ 37	$ 12

Nominal or face amount used to calculate payments on the derivative liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

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