EMPLOYEE BENEFIT PLANS - Net Periodic Pension Cost (Credit) (Details) - Defined Benefit Pension Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 23	$ 4	$ 47	$ 8
Interest cost	588	597	1,189	1,176
Expected return on plan assets	(948)	(761)	(1,918)	(1,499)
Amortization of net actuarial loss	0	17	0	34
Net periodic pension credit	$ (337)	$ (143)	$ (682)	$ (281)