PENSION AND OTHER POSTRETIREMENT PLANS - Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 153	$ (372)	$ (211)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	1,464	1,242
SERP Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 597	$ 615

Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent.

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