ACCUMULATED OTHER COMPREHENSIVE LOSS (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Accumulated Other Comprehensive Loss [Abstract]
Unrecognized prior service credits	$ (2,075)
Unrecognized prior service credits, net of tax	(1,940)
Unrecognized actuarial losses	11,912
Unrecognized actuarial losses, net of tax	8,290
Prior service credit expected to be recognized, next fiscal year	229
Prior service credit expected to be recognized, next fiscal year, net of tax	181
Actuarial losses expected to be recognized, next fiscal year	568
Actuarial losses expected to be recognized, next fiscal year, net of tax	$ 449