EMPLOYEE RELATED LIABILITIES (Schedule of Components of Change in Benefit Obligation, Change in Plan Assets and Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in medical plan related benefit obligation:
Change in medical plan provisions		$ (3,900)
Postretirement Medical Plan [Member]
Change in medical plan related benefit obligation:
Medical plan related benefit obligation at beginning of period	$ 1,550	1,781	$ 2,977
Service cost	9	12	29
Interest cost	69	85	126
Benefits paid	(9)	(12)	(18)
Change in medical plan provisions
Actuarial loss (gain)	317	(316)	(1,333)
Benefit medical plan related obligation end of period	1,936	1,550	1,781
Change in plan assets
Fair value of plan assets at beginning of period
Employer contributions	9	12	18
Benefits paid	(9)	(12)	(18)
Fair value of plan assets at end of period
Medical plan related net funding	(1,936)	(1,550)	(1,781)
Pension Plan [Member]
Change in medical plan related benefit obligation:
Medical plan related benefit obligation at beginning of period	19,672	18,605	19,304
Interest cost	831	841	798
Benefits paid	(548)	(496)	(451)
Change in medical plan provisions
Actuarial loss (gain)	674	722	(1,046)
Benefit medical plan related obligation end of period	20,629	19,672	18,605
Change in plan assets
Fair value of plan assets at beginning of period	19,871	18,526	18,134
Actual return on plan assets	3,212	1,141	78
Employer contributions	700	700	765
Benefits paid	(548)	(496)	(451)
Fair value of plan assets at end of period	23,235	19,871	18,526
Medical plan related net funding	$ 2,606	$ 199	$ (79)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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-Publisher FASB
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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No definition available.

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No definition available.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 20
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Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 60
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-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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