PENSION AND OTHER POST-EMPLOYMENT BENEFITS - Healthcare Rate Trends (Details) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation, Health Care Cost Ultimate Trend Rate	4.50%
Defined Benefit Plan, Net Periodic Benefit Cost, Health Care Cost Ultimate Trend Rate	4.50%
Defined Benefit Plan, Prescription Drug Cost Trend Rate Assumed, Next Fiscal Year	10.10%
Defined Benefit Plan, Benefit Obligation, Prescription Drug Cost Ultimate Trend Rate	4.50%
Defined Benefit Plan, Net Periodic Benefit Cost, Prescription Drug Cost Trend Rate Assumed, Next Fiscal Year	11.10%
Defined Benefit Plan, Net Periodic Benefit Cost, Prescription Drug Cost Ultimate Trend Rate	4.50%
Effect of 1% increase on accumulated postretirement benefit obligation	$ 9
Effect of 1% decrease in benefit obligation	8
Effect of 1% increase on service and interest cost components	1
Effect of 1% decrease in service and interest cost components	$ 1
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation, Health Care Cost Trend Rate Assumed, Next Fiscal Year	5.60%
Defined Benefit Plan, Net Periodic Benefit Cost, Health Care Cost Trend Rate Assumed, Next Fiscal Year	5.80%
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7.20%
Defined Benefit Plan, Net Periodic Benefit Cost, Health Care Cost Trend Rate Assumed, Next Fiscal Year	6.20%