EMPLOYEE BENEFIT PLAN - Unrealized gains, net related to the SERP assets (Details 1) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Non-qualified Supplemental Retirement Plan ("SERP")
Defined Benefit Plan Disclosure [Line Items]
Unrealized gains, net	$ 871	$ 936	$ 385	$ 1,552

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.

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