EMPLOYEE BENEFIT PLANS (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($) Plan	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Defined benefit plan [Abstract]
Number of defined benefit plans | Plan	2
Defined Benefit Plan, Type [Extensible List]	us-gaap:DefinedBenefitPostretirementHealthCoverageMember
Defined Benefit Plan, Funding Status [Extensible List]	us-gaap:UnfundedPlanMember
Components of net periodic benefit cost [Abstract]
Service cost	$ 58	$ 50
Interest cost	33	35
Amortization of prior service cost	52	55
Amortization of gain	(2)	(11)
Net periodic benefit cost	141	$ 129
Amount recognized in consolidated balance sheet for benefit obligations (included in other long-term obligations)	1,664		$ 1,573
Maximum [Member]
Components of net periodic benefit cost [Abstract]
Historical cash payments for retirement medical plan claims per year	100
Unfunded, Nonqualified Deferred Compensation Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation liability	$ 124