Loans and asset quality- Troubled Debt Restructurings (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014 Contract	Dec. 31, 2013 Contract	Mar. 31, 2013 Contract
Financing Receivable, Modifications [Line Items]
Number of contracts (contracts)	32	30	31
Outstanding recorded investment Pre-modification	$ 10	$ 6	$ 5
Outstanding recorded investment Post- modification	9	8	6
Domestic \| Other residential mortgages
Financing Receivable, Modifications [Line Items]
Number of contracts (contracts)	31	30	31
Outstanding recorded investment Pre-modification	5	6	5
Outstanding recorded investment Post- modification	5	8	6
Foreign
Financing Receivable, Modifications [Line Items]
Number of contracts (contracts)	1	0	0
Outstanding recorded investment Pre-modification	5	0	0
Outstanding recorded investment Post- modification	$ 4	$ 0	$ 0

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524

+ Details

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- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

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- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

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