PENSION PLAN AND OTHER BENEFIT PLANS - Amounts Recognized, Assumptions Used, Target and Actual Allocation, Fair Value, Estimated Future Benefit Payments, and Other Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	$ 626	$ 711	$ (1,001)
Recognized actuarial loss	312	318	413
Prior service credit	0	0	0
Amortization of prior service benefit	(220)	(220)	(220)
Total before tax effect	(534)	215	1,194
Pension Plan
Amount recognized in accumulated other comprehensive income [Abstract]
Net actuarial loss	9,352	9,075
Prior service cost	0	0
Total before tax effects	9,352	9,075
Accumulated benefit obligation	39,900	36,000
Net periodic benefit cost [Abstract]
Service cost	0	0	0
Interest cost	1,522	1,551	1,646
Expected return on plan assets	(2,221)	(3,309)	(3,144)
Recognized actuarial loss	204	188	267
Amortization of prior service cost	0	0	0
Recognized (gain) loss due to settlements	0	828	0
Net periodic cost (benefit)	(495)	(742)	(1,231)
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	481	736	(1,165)
Recognized actuarial loss	(204)	(1,016)	(267)
Amortization of prior service benefit	0	0	0
Total before tax effect	277	(280)	(1,432)
Total recognized in net (benefit) cost and other comprehensive income (loss) (before tax effect)	$ (218)	$ (1,022)	$ (2,663)
Unrecognized net gain or loss increase threshold percentage for amortization of obligation (in hundredths)	10.00%
Amounts expected to be recognized in net periodic cost during next fiscal year [Abstract]
Loss recognition	$ 196
Prior service cost recognition	$ 0
Weighted-average assumptions for net periodic cost [Abstract]
Discount rate	4.35%	3.74%	4.16%
Expected long-term rate of return on assets	5.50%	7.25%	7.75%
Discount rate	3.33%	4.35%	3.74%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	100.00%	100.00%
Expected long-term rate of return on assets	5.50%	7.25%	7.75%
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 45,557	$ 41,476	$ 46,672
Estimated benefit payments for each of next five years and aggregate amount expected to be paid [Abstract]
2020	2,223
2021	2,240
2022	2,251
2023	2,251
2024	2,269
2025-2029	$ 11,350
Pension Plan | Minimum
Effect of a 1% decrease in health care trend rate on:
Evaluation period of expected long-term return on plan assets	3 years
Pension Plan | Maximum
Effect of a 1% decrease in health care trend rate on:
Evaluation period of expected long-term return on plan assets	5 years
Pension Plan | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 45,557	41,476
Pension Plan | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	41,477	37,962
Pension Plan | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	4,080	3,514
Pension Plan | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0
Pension Plan | Large-Cap Domestic Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	7.50%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	38.00%	38.00%
Expected long-term rate of return on assets	7.50%
Pension Plan | Large-Cap Domestic Equities | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	20.00%
Pension Plan | Large-Cap Domestic Equities | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	50.00%
Pension Plan | Mid-Cap Domestic Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	9.50%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	2.00%	2.00%
Expected long-term rate of return on assets	9.50%
Pension Plan | Mid-Cap Domestic Equities | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Pension Plan | Mid-Cap Domestic Equities | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	15.00%
Pension Plan | Small-Cap Domestic Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	7.80%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	2.00%	6.00%
Expected long-term rate of return on assets	7.80%
Pension Plan | Small-Cap Domestic Equities | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Pension Plan | Small-Cap Domestic Equities | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	10.00%
Pension Plan | Equity Securities - International Companies
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	4.70%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	8.00%	4.00%
Expected long-term rate of return on assets	4.70%
Pension Plan | Equity Securities - International Companies | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Pension Plan | Equity Securities - International Companies | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	20.00%
Pension Plan | Equity Securities - International Companies | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0
Pension Plan | Equity Securities - International Companies | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets		0
Pension Plan | Equity Securities - International Companies | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Equity Securities - International Companies | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0
Pension Plan | Intermediate Fixed Income
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	4.60%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	45.00%	37.00%
Expected long-term rate of return on assets	4.60%
Pension Plan | Intermediate Fixed Income | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	30.00%
Pension Plan | Intermediate Fixed Income | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	70.00%
Pension Plan | Alternative Assets
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	0.00%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	0.00%	0.00%
Expected long-term rate of return on assets	0.00%
Pension Plan | Alternative Assets | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Pension Plan | Alternative Assets | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	10.00%
Pension Plan | Cash
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	1.30%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	5.00%	13.00%
Expected long-term rate of return on assets	1.30%
Pension Plan | Cash | Minimum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Pension Plan | Cash | Maximum
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	20.00%
Pension Plan | Cash | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 2,210	$ 5,476
Pension Plan | Cash | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	2,210	5,476
Pension Plan | Cash | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Cash | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Equity Securities - U.S. Companies | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	17,939	16,244
Pension Plan | Equity Securities - U.S. Companies | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	17,939	16,244
Pension Plan | Equity Securities - U.S. Companies | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Equity Securities - U.S. Companies | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Mutual Funds | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	21,328	16,242
Pension Plan | Mutual Funds | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	21,328	16,242
Pension Plan | Mutual Funds | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Mutual Funds | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | U.S. Treasuries/Government Bonds | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	3,054	2,031
Pension Plan | U.S. Treasuries/Government Bonds | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | U.S. Treasuries/Government Bonds | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	3,054	2,031
Pension Plan | U.S. Treasuries/Government Bonds | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Corporate bonds and notes | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	1,026	1,483
Pension Plan | Corporate bonds and notes | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Corporate bonds and notes | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	1,026	1,483
Pension Plan | Corporate bonds and notes | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Defined Benefit Health Care Plan
Amount recognized in accumulated other comprehensive income [Abstract]
Net actuarial loss	417	491
Prior service cost	(440)	(661)
Total before tax effects	(23)	(170)
Net periodic benefit cost [Abstract]
Service cost	0	0	0
Interest cost	16	16	20
Recognized actuarial loss	105	123	143
Recognized prior service benefit due to curtailments	0	0	0
Amortization of prior service cost	(220)	(220)	(220)
Net periodic cost (benefit)	(99)	(81)	(57)
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	(31)	(22)	(98)
Recognized actuarial loss	(105)	(123)	(143)
Prior service credit	0	0	0
Amortization of prior service benefit	220	220	220
Total before tax effect	146	119	175
Total recognized in net (benefit) cost and other comprehensive income (loss) (before tax effect)	$ 47	$ 38	$ 118
Average future working lifetime of active participants	5 years
Amounts expected to be recognized in net periodic cost during next fiscal year [Abstract]
Loss recognition	$ 96
Prior service cost recognition	$ (220)
Weighted-average assumptions for net periodic cost [Abstract]
Discount rate	4.35%	3.74%	4.16%
Discount rate	3.33%	4.35%	3.74%
Health care cost trend rate assumed, next fiscal year			6.50%
Health care cost trend: Ultimate (Pre-65/Post 65)		5.00%	5.00%
Health care cost trend: Initial		6.50%	6.50%
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0
Estimated benefit payments for each of next five years and aggregate amount expected to be paid [Abstract]
2020	86
2021	50
2022	37
2023	38
2024	21
2025-2029	87
Effect of a 1% increase in health care trend rate on:
Benefit obligation	17	4	5
Total service and interest cost	1	0	0
Effect of a 1% decrease in health care trend rate on:
Benefit obligation	(16)	(4)	(6)
Total service and interest cost	(1)	$ 0	0
Estimated employer contributions in next fiscal year	$ 86
Defined Benefit Health Care Plan | Minimum
Weighted-average assumptions for net periodic cost [Abstract]
Health care cost trend rate assumed, next fiscal year	6.95%	6.95%
Health care cost trend: Ultimate (Pre-65/Post 65)	4.75%	4.75%
Defined Benefit Health Care Plan | Maximum
Weighted-average assumptions for net periodic cost [Abstract]
Health care cost trend rate assumed, next fiscal year	5.45%	5.45%
Health care cost trend: Ultimate (Pre-65/Post 65)	4.75%	4.75%
Executive Supplemental Pension Plan
Amount recognized in accumulated other comprehensive income [Abstract]
Net actuarial loss	$ 283	$ 174
Prior service cost	0	0
Total before tax effects	283	174
Accumulated benefit obligation	1,200	1,200
Net periodic benefit cost [Abstract]
Service cost	0	0	0
Interest cost	49	46	50
Recognized actuarial loss	4	7	3
Net periodic cost (benefit)	53	53	53
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	(113)	47	(66)
Recognized actuarial loss	(4)	(7)	(3)
Total before tax effect	109	(54)	63
Total recognized in net (benefit) cost and other comprehensive income (loss) (before tax effect)	$ 162	$ (1)	$ 116
Unrecognized net gain or loss increase threshold percentage for amortization of obligation (in hundredths)	10.00%
Amounts expected to be recognized in net periodic cost during next fiscal year [Abstract]
Loss recognition	$ 13
Prior service cost recognition	$ 0
Weighted-average assumptions for net periodic cost [Abstract]
Discount rate	4.35%	3.74%	4.16%
Discount rate	3.33%	4.35%	3.74%
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0
Estimated benefit payments for each of next five years and aggregate amount expected to be paid [Abstract]
2020	109
2021	107
2022	105
2023	102
2024	99
2025-2029	431
Effect of a 1% decrease in health care trend rate on:
Estimated employer contributions in next fiscal year	$ 110