BENEFIT PLANS (Contributions by Participants to Postretirement Benefit Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Participants Contributions	$ 2,025	$ 2,085	$ 2,031

Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration