PENSION AND SUPPLEMENTAL EXECUTIVE RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Plan
Components of net periodic benefit cost
Interest cost	$ 167	$ 233	$ 398	$ 462
Expected return on plan assets	(345)	(264)	(604)	(528)
Amortization of net actuarial loss	192	300	490	596
Net periodic cost	14	269	284	530
SERPs
PENSION AND SUPPLEMENTAL EXECUTIVE RETIREMENT PLANS
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	(138)	0	(138)
Components of net periodic benefit cost
Interest cost	98	100	195	215
Amortization of net actuarial loss	43	25	86	51
Amortization of net transition obligation	4	5	9	9
Amortization of prior service cost	4	4	9	8
Net periodic cost	$ 149	$ 272	$ 299	$ 421

Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

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- Definition

Amount of transition asset (obligation) recognized in net periodic benefit (cost) credit of defined benefit plan.

+ References

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+ References

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- Definition

Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan.

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- Definition

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

+ 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 (h)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of net periodic benefit cost (credit) for defined benefit plan.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

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- Definition

Amount of gain (loss) recognized in net periodic benefit (cost) credit from settlement and curtailment.

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