ACCUMULATED OTHER COMPREHENSIVE LOSS - Details about Accumulated Other Comprehensive Income Components (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense (benefit)	$ 502	$ 1,034
Pension and other employee benefits	1,516	1,545
Net income	2,491	4,468
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	21	13
Prior service costs | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension and other employee benefits	(55)	(55)
Actuarial losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pension and other employee benefits	77	73
Defined Benefit and Other Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense (benefit)	(1)	(5)
Net income	$ 21	$ 13