EMPLOYEE BENEFITS (Assumptions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assumptions Used to Determine Benefit Obligations [Abstract]
Rate of compensation increase	3.00%	3.00%
Assumptions Used to Determine Net Periodic Benefit Cost [Abstract]
Expected long-term rate of return on plan assets	7.50%	7.50%	7.50%
Rate of compensation increase	3.00%	3.00%	3.00%
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of 1% increase on the net periodic postretirement health care benefit cost	$ 1,126
Effect of 1% decrease on the net periodic postretirement health care benefit cost	(883)
Effect of 1% increase on the accumulated postretirement benefit obligation	9,487
Effect of 1% decrease on the accumulated postretirement benefit obligation	$ (7,698)
Pension Benefits
Assumptions Used to Determine Benefit Obligations [Abstract]
Discount rate	3.65%	4.17%
Assumptions Used to Determine Net Periodic Benefit Cost [Abstract]
Discount rate	4.17%	4.21%	3.86%
Post-retirement Benefits
Assumptions Used to Determine Benefit Obligations [Abstract]
Discount rate	3.65%	4.17%
Assumptions Used to Determine Net Periodic Benefit Cost [Abstract]
Discount rate	4.17%	4.21%	3.86%
Health Care Benefits
Assumed Health Care Cost Trend Rates [Abstract]
Health care cost trend rates assumed for next year	7.00%	7.00%
Rate to which the health care trend rate is assumed to decline (ultimate trend rate)	4.50%	4.50%
Dental Claims
Assumed Health Care Cost Trend Rates [Abstract]
Health care cost trend rates assumed for next year	4.00%	4.00%