EMPLOYEE BENEFIT PLANS - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	$ 19,901	$ 16,366	$ 17,486
Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	19,901	16,366
Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1,058	770
Cash and cash equivalents | Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1,058	770
Cash and cash equivalents | Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Cash and cash equivalents | Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Mutual funds - taxable fixed income
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	2,240	2,120
Mutual funds - taxable fixed income | Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	2,240	2,120
Mutual funds - taxable fixed income | Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Mutual funds - taxable fixed income | Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Mutual funds - domestic equity
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	10,797	8,550
Mutual funds - domestic equity | Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	10,797	8,550
Mutual funds - domestic equity | Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Mutual funds - domestic equity | Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Mutual funds - international equity
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	2,565	1,970
Mutual funds - international equity | Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	2,565	1,970
Mutual funds - international equity | Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Mutual funds - international equity | Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Inflation Hedges/Real Assets
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1,145	965
Inflation Hedges/Real Assets | Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1,145	965
Inflation Hedges/Real Assets | Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Inflation Hedges/Real Assets | Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Hedged Strategies
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	2,096	1,991
Hedged Strategies | Level I
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	2,096	1,991
Hedged Strategies | Level II
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Hedged Strategies | Level III
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	$ 0	$ 0