PENSION PLANS - Fair values and asset allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value	$ 13,009	$ 10,852	$ 12,120
Level 1
Fair Value	$ 13,009	$ 11,138
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Cash and Cash Equivalents [Member] | Level 1
Fair Value	$ 835	$ 557
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	6.00%	5.00%
Cash and Cash Equivalents [Member] | Level 1 | Maximum [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%
Cash and Cash Equivalents [Member] | Level 1 | Minimum [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
Equity Securities [Member] | Level 1
Fair Value	$ 8,019	$ 6,460
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	62.00%	58.00%
Equity Securities [Member] | Level 1 | Maximum [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	57.00%
Equity Securities [Member] | Level 1 | Minimum [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
Fixed income securities [Member] | Level 1
Fair Value	$ 4,155	$ 4,121
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	32.00%	37.00%
Fixed income securities [Member] | Level 1 | Maximum [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	50.00%
Fixed income securities [Member] | Level 1 | Minimum [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	35.00%