Servicing Rights and Residual Interests Economic Assumptions (Detail)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Fixed Rate Residential Mortgage
Assumption For Fair Value As Of Balance Sheet Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Weighted- Average Life (in years)	6 years 6 months	7 years 3 months 18 days
Prepayment Speed (annual)	11.30%	9.10%
Discount Rate (annual)	10.00%	10.20%
Adjustable Rate Residential Mortgage
Assumption For Fair Value As Of Balance Sheet Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Weighted- Average Life (in years)	3 years 9 months 18 days	3 years 7 months 6 days
Prepayment Speed (annual)	22.30%	22.80%
Discount Rate (annual)	11.70%	11.50%

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Weighted average life of securitized assets regardless of when the transfer occurred, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)(2)

-URI http://asc.fasb.org/extlink&oid=13989330&loc=d3e107314-111719

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- Definition

Discount rate which is used to value residual cash flows generated by financial assets of a securitization, asset-backed financing arrangement, or similar transfer regardless of when the transfer occurred.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=13989330&loc=d3e107314-111719

+ Details

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- Definition

Estimated rate of prepayment of principal on financial assets regardless of when the transfer occurred.

+ References

+ Details

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