ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax (benefit) expense	$ 5,667	$ 5,764
Net of tax	211
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credits	(182)	(371)
Actuarial losses	(348)	(155)
Total before tax	166	(216)
Tax (benefit) expense	(45)	(79)
Net of tax	$ 211	$ (137)