FAIR VALUE MEASUREMENTS - Unobservable Inputs Recurring (Details) $ in Thousands	Jun. 30, 2019 USD ($) $ / contract	Dec. 31, 2018 USD ($) $ / contract
Quantitative information about the significant unobservable inputs within Level 3
Trading security	$ 11,210	$ 11,212
Level 3 \| Recurring
Quantitative information about the significant unobservable inputs within Level 3
Trading security	11,210	11,212
Total	$ 31,421	$ 26,624
Level 3 \| Recurring \| Discounted Cash Flow \| Discount rate
Quantitative information about the significant unobservable inputs within Level 3
Trading security, significant unobservable input value	0.0228	0.0307
Level 3 \| Recurring \| Commitments to lend
Quantitative information about the significant unobservable inputs within Level 3
Derivative asset	$ 9,005	$ 3,927
Level 3 \| Recurring \| Commitments to lend \| Historical Trend \| Closing Ratio
Quantitative information about the significant unobservable inputs within Level 3
Derivative asset, significant unobservable input value	0.7248	0.8236
Level 3 \| Recurring \| Commitments to lend \| Pricing Model \| Origination Costs, per loan
Quantitative information about the significant unobservable inputs within Level 3
Derivative asset, significant unobservable input value \| $ / contract	3,137	3,063
Level 3 \| Recurring \| Capitalized servicing rights
Quantitative information about the significant unobservable inputs within Level 3
Servicing asset	$ 11,206	$ 11,485
Level 3 \| Recurring \| Capitalized servicing rights \| Discounted Cash Flow \| Discount rate
Quantitative information about the significant unobservable inputs within Level 3
Servicing asset, significant unobservable input value	0.0999	0.1000
Level 3 \| Recurring \| Capitalized servicing rights \| Discounted Cash Flow \| Constant prepayment rate (CPR)
Quantitative information about the significant unobservable inputs within Level 3
Servicing asset, significant unobservable input value	0.1274	0.0930

Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in net income (trading).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Fair value of asset after deduction of liability.

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Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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