EMPLOYEE BENEFIT PLAN - Trading results related to SERP (Details 1) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Non-qualified Supplemental Retirement Plan ("SERP")
Defined Benefit Plan Disclosure [Line Items]
Trading gains (losses), net	$ 977	$ (1,424)	$ 713	$ (1,030)

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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