EMPLOYEE BENEFITS (Assumptions) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of 1% increase on the net periodic postretirement health care benefit cost	$ 643
Effect of 1% decrease on the net periodic postretirement health care benefit cost	(494)
Effect of 1% increase on the accumulated postretirement benefit obligation	5,520
Effect of 1% decrease on the accumulated postretirement benefit obligation	$ (4,451)
Pension Benefits
Assumptions Used to Determine Benefit Obligations [Abstract]
Discount rate	2.58%	3.32%
Rate of compensation increase	2.75%	3.00%
Assumptions Used to Determine Net Periodic Benefit Cost [Abstract]
Discount rate	3.32%	4.18%	3.65%
Expected long-term rate of return on plan assets	6.70%	6.70%	6.70%
Rate of compensation increase	3.00%	3.00%	3.00%
Post-retirement Benefits
Assumptions Used to Determine Benefit Obligations [Abstract]
Discount rate	2.58%	3.32%
Assumptions Used to Determine Net Periodic Benefit Cost [Abstract]
Discount rate	3.32%	4.18%	3.65%
Health Care Benefits
Assumed Health Care Cost Trend Rates [Abstract]
Health care cost trend rates assumed for next year	7.00%	6.75%
Rate to which the health care trend rate is assumed to decline (ultimate trend rate)	4.50%	4.50%
Dental Claims
Assumed Health Care Cost Trend Rates [Abstract]
Health care cost trend rates assumed for next year	3.00%	4.00%

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Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

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Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

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Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2919-114920

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Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

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Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
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-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate.

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Amount of increase in accumulated postretirement benefit obligation from one-percentage-point increase in assumed health care cost trend rate.

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Amount of increase in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point increase in assumed health care cost trend rate.

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Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

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Ultimate trend rate for health care cost for defined benefit postretirement plan.

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