EMPLOYEE BENEFIT PLANS (Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Weighted Average Assumptions Used to Determine Benefit Obligations
Discount rate	2.36%	3.21%
Rate of compensation increase	4.28%	4.28%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Expected long-term rate of return on plan assets	5.75%	6.00%	6.25%
Rate of compensation increase	4.28%	4.55%	4.53%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate	2.19%	3.34%	2.88%
Pension Benefits [Member] | Service Cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.94%	4.24%	3.62%
Pension Benefits [Member] | Effective rate for interest cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.50%	3.92%	3.21%
Pension Benefits [Member] | Effective rate for interest on service cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.59%	4.00%	3.32%
Supplemental Employee Retirement Plan [Member]
Weighted Average Assumptions Used to Determine Benefit Obligations
Discount rate	2.21%	3.09%
Rate of compensation increase	4.50%	4.50%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Rate of compensation increase	4.50%	5.00%	5.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate	2.19%	3.34%	2.88%
Supplemental Employee Retirement Plan [Member] | Service Cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.79%	4.19%	3.58%
Supplemental Employee Retirement Plan [Member] | Effective rate for interest cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.33%	3.83%	3.15%
Supplemental Employee Retirement Plan [Member] | Effective rate for interest on service cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.42%	3.90%	3.24%
Post Retirement Medical Plan [Member]
Weighted Average Assumptions Used to Determine Benefit Obligations
Discount rate	1.90%	2.88%
Rate of compensation increase	0.00%	0.00%
Post Retirement Medical Plan [Member] | Service Cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.86%	4.21%	3.59%
Post Retirement Medical Plan [Member] | Effective rate for interest cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.21%	3.69%	2.97%
Post Retirement Medical Plan [Member] | Effective rate for interest on service cost [Member]
Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs
Discount rate	2.68%	4.09%	3.46%