Troubled Debt Restructurings (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of contracts	34
Outstanding recorded investment Pre-modification	$ 59
Outstanding recorded investment Post- modification	55
Domestic \| Commercial
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Outstanding recorded investment Pre-modification	38
Outstanding recorded investment Post- modification	32
Domestic \| Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of contracts	2
Outstanding recorded investment Pre-modification	11
Outstanding recorded investment Post- modification	12
Domestic \| Other Residential Mortgages
Financing Receivable, Modifications [Line Items]
Number of contracts	30
Outstanding recorded investment Pre-modification	7
Outstanding recorded investment Post- modification	8
Foreign
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Outstanding recorded investment Pre-modification	3
Outstanding recorded investment Post- modification	$ 3

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The 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 32

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953670-111524

Reference 2: 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=6965416&loc=SL6953676-111524

+ Details

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings after the financing receivable has been modified.

+ References

+ Details

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings before the financing receivable has been modified.

+ References

+ Details

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