INVESTMENT SECURITIES - Significant Assumptions in Valuation of Private Label MBS (Detail)	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Schedule Of Investments [Line Items]
Fair Value Inputs Discount Rate	14.50%	14.50%
Fair Value Inputs Prepayment Rate	30.00%	28.00%
Weighted Average, Projected Cumulative Loss Rate	7.00%	7.00%
Minimum [Member]
Schedule Of Investments [Line Items]
Fair Value Inputs Prepayment Rate	21.45%	15.92%
Weighted Average, Projected Cumulative Loss Rate	0.50%	0.18%
Maximum [Member]
Schedule Of Investments [Line Items]
Fair Value Inputs Prepayment Rate	100.00%	100.00%
Weighted Average, Projected Cumulative Loss Rate	80.00%	80.00%

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=36462937&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

+ Details

Name:	us-gaap_FairValueInputsLossSeverity
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_FairValueInputsPrepaymentRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_ScheduleOfInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: