Variable Interest Entities - Summary of Geographic Concentrations of Residential Mortgage Loans Held-for-Investment (Parenthetical) (Detail)	9 Months Ended
Sep. 30, 2015
Variable Interest Entity Primary Beneficiary \| Geographic Concentration Risk \| Residential Loans Held For Investment
Concentration Risk [Line Items]
Concentration risk percentage on other state	5.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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