POSTRETIREMENT BENEFITS (Details 4) - Other Postretirement Benefit Plans, Defined Benefit	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted Average Assumptions [Abstract]
Discount rate—periodic benefit cost	3.10%	4.10%	3.50%
Discount rate—benefit obligation	2.30%	3.10%	4.10%