Loan Modifications Determined to be Troubled Debt Restructuring (Detail) (Residential Loans, USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Contract	Dec. 31, 2013 Contract	Dec. 31, 2012 Contract
Residential Loans
Financing Receivable, Modifications [Line Items]
Number of modifications	28	12	15
Pre-modification outstanding recorded investment	$ 8,652	$ 2,939	$ 6,603
Post-modification outstanding recorded investment	8,639	2,838	6,540
Loan modification effect on net interest income after provision and other MVA	(2,214)	(863)	(1,448)
Number of modifications	7	6	10
Recorded investment	$ 3,427	$ 1,462	$ 5,078

Financing Receivable Modifications Effect on Net Interest Income

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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=35738203&loc=SL6953676-111524

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

+ References

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

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 34

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953682-111524

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Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

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