ACCUMULATED OTHER COMPREHENSIVE LOSS - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ 1,034	$ 1,061
Other components of net periodic pension and postretirement benefits	(141)	(408)
Net income	(4,468)	(4,439)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income	13	13
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	(5)	(5)
Prior Service Costs | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other components of net periodic pension and postretirement benefits	(55)	(55)
Actuarial Losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other components of net periodic pension and postretirement benefits	$ 73	$ 73