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EMPLOYEE BENEFIT PLANS (Nonunion Plan Assets - FV) (Details) - Nonunion Defined Benefit Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and other postretirement benefit plans
Fair value of plan assets	$ 124,831	$ 144,805	$ 136,917
Cash and Cash Equivalents
Pension and other postretirement benefit plans
Fair value of plan assets	16,641	23,696
Debt Instruments
Pension and other postretirement benefit plans
Fair value of plan assets	91,778	36,245
Floating Rate Loan Fund
Pension and other postretirement benefit plans
Fair value of plan assets	16,412	15,687
Large Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets		20,208
Mid Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets		13,597
Small Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets		14,561
International Equity
Pension and other postretirement benefit plans
Fair value of plan assets		20,811
Level 1
Pension and other postretirement benefit plans
Fair value of plan assets	43,140	108,560
Level 1 | Cash and Cash Equivalents
Pension and other postretirement benefit plans
Fair value of plan assets	16,641	23,696
Level 1 | Debt Instruments
Pension and other postretirement benefit plans
Fair value of plan assets	10,087
Level 1 | Floating Rate Loan Fund
Pension and other postretirement benefit plans
Fair value of plan assets	16,412	15,687
Level 1 | Large Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets		20,208
Level 1 | Mid Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets		13,597
Level 1 | Small Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets		14,561
Level 1 | International Equity
Pension and other postretirement benefit plans
Fair value of plan assets		20,811
Level 2
Pension and other postretirement benefit plans
Fair value of plan assets	81,691	36,245
Level 2 | Debt Instruments
Pension and other postretirement benefit plans
Fair value of plan assets	$ 81,691	$ 36,245
Level 2 | Corporate debt securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	80.00%	81.00%
Level 2 | Mortgage-backed instruments
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	4.00%	10.00%
Level 2 | Treasury instruments
Pension and other postretirement benefit plans
Percentage of investments in debt instruments		7.00%
Level 2 | Municipal debt securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments		1.00%
Level 2 | Asset-backed securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	16.00%
Level 2 | Agency securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments		1.00%

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- Definition

Represents the percentage of the entity's defined benefit pension plan investments in debt instruments that belong to a particular class or type of security.

+ References

No definition available.

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- Definition

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+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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