EMPLOYEE RETIREMENT PLANS - Assumptions Used to Determine Net Periodic Pension Cost (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assumptions used to determine the net periodic pension cost [Abstract]
Discount rate	2.64%	3.82%	3.22%
Rate of compensation increases	3.50%	3.50%	3.50%