INVESTMENT SECURITIES - Significant Assumptions in Valuation of Private Label MBS (Detail)	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Schedule Of Investments [Line Items]
Fair Value Inputs Discount Rate	14.20%	14.10%
Fair Value Inputs Prepayment Rate	16.50%	13.80%
Weighted Average, Projected Cumulative Loss Rate	4.00%	4.00%
Minimum [Member]
Schedule Of Investments [Line Items]
Fair Value Inputs Discount Rate		12.88%
Fair Value Inputs Prepayment Rate	12.00%	6.50%
Weighted Average, Projected Cumulative Loss Rate	0.10%	0.20%
Maximum [Member]
Schedule Of Investments [Line Items]
Fair Value Inputs Discount Rate		14.43%
Fair Value Inputs Prepayment Rate	29.00%	22.50%
Weighted Average, Projected Cumulative Loss Rate	7.10%	8.60%

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Loss, including interest and principal, incurred on a defaulted security, expressed as a percentage of the original principal balance, used as an input to measure fair value.

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Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value.

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- Definition

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.

+ References

No definition available.

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