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INVESTMENT SECURITIES - Significant Assumptions in Valuation of Private Label MBS (Detail) - Private label MBS [Member] | Sep. 30, 2018 | Dec. 31, 2017
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Discount rate [Member] | Weighted Average [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.148 | 0.14
Discount rate [Member] | Minimum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.148 | 0.14
Discount rate [Member] | Maximum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.148 | 0.14
Prepayment rate [Member] | Weighted Average [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.117 | 0.164
Prepayment rate [Member] | Minimum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.035 | 0.12
Prepayment rate [Member] | Maximum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.225 | 0.29
Projected Cumulative Loss Rate [Member] | Weighted Average [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.04 | 0.03
Projected Cumulative Loss Rate [Member] | Minimum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0 | 0
Projected Cumulative Loss Rate [Member] | Maximum [Member] |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |
Debt Securities, Available-for-sale, Measurement Input | 0.078 | 0.068

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- Definition Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
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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. + Details
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