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POSTRETIREMENT BENEFITS (Details 5) - Other Postretirement Benefit Plans, Defined Benefit
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Assumed healthcare cost trend rates [Abstract]    
Healthcare cost trend rate assumed for next year 7.50% 7.50%
Rate that the cost trend rate gradually declines to 4.50% 4.50%
Year that the rate reaches the ultimate rate 2031 2024