EMPLOYEE BENEFIT PLANS - ASSUMPTIONS (Details) - Qualified Defined Benefit [Member]	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Minimum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate	2.43%	3.33%	4.37%
Benefit obligations, Rate of compensation increase	2.02%	2.11%	2.11%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Weighted-average discount rate	3.33%	4.37%	3.69%
Net period benefit costs, Weighted-average expected return on assets	3.25%	4.25%	4.25%
Net period benefit costs, Rate of compensation increase	2.11%	2.11%	2.11%
Maximum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Benefit obligations, Weighted-average discount rate	2.58%	3.47%	4.46%
Benefit obligations, Rate of compensation increase	2.43%	5.44%	3.50%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Net period benefit costs, Weighted-average discount rate	3.47%	4.46%	3.78%
Net period benefit costs, Weighted-average expected return on assets	5.50%	5.50%	5.50%
Net period benefit costs, Rate of compensation increase	5.44%	3.50%	16.51%