EMPLOYEE BENEFIT PLANS (Plans) (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2014 USD ($) person	Dec. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)
Nonunion Defined Benefit Pension Plan
Nonunion Defined Benefit Pension, Supplemental Benefit, and Postretirement Health Benefit Plans
Number of plan participants for which vested pension benefits were settled | person	375
Premium paid to purchase nonparticipating annuity contract	$ 25,400		$ 25,400
Pension benefit obligation settled with nonparticipating annuity contract	$ 23,300
Lump-sum distributions			$ 32,100
Unrecognized net actuarial loss		$ 23,294		$ 28,457
Amortization period for unrecognized net actuarial loss		8 years
Postretirement Health Benefit Plan
Nonunion Defined Benefit Pension, Supplemental Benefit, and Postretirement Health Benefit Plans
Unrecognized net actuarial loss		$ 5,708		$ 6,280
Unrecognized prior service credit, amortization period		9 years