EMPLOYEE BENEFITS - Assumptions Used to Calculate Benefit Obligation, Net Periodic Benefit Cost and Postretirement Benefit (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Pension Plan
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.32%	3.71%
Compensation increase rate	3.50%	3.50%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.71%	4.23%	4.56%
Expected long-term rate of return on plan assets	7.25%	7.25%	7.25%
Compensation increase rate	3.50%	3.50%	3.50%
Defined Benefit Pension Plan Acquired
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.32%	3.71%
Compensation increase rate	0.00%	0.00%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.71%	4.23%	4.56%
Expected long-term rate of return on plan assets	7.25%	7.25%	7.25%
Compensation increase rate	0.00%	0.00%	0.00%
Restoration Plan
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.32%	3.71%
Compensation increase rate	3.50%	3.50%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.71%	4.23%	4.56%
Compensation increase rate	3.50%	3.50%	3.50%