PENSION AND POSTRETIREMENT WELFARE PLANS - Postretirement Welfare Plan (Details) - Postretirement Welfare Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Pension and Postretirement plan
Requisite service period for employees who retire after January 1, 2005 in order to be eligible for retiree medical benefits	20 years
Change in postretirement benefit obligation:
Accumulated post retirement benefit obligation at beginning of period	$ 1,288	$ 1,408
Service cost	10	9
Interest cost	50	57
Actuarial (gain) loss	(204)	(138)
Benefits paid	(49)	(88)
Participant contributions		40
Accumulated post retirement benefit obligation at end of period	$ 1,095	$ 1,288