REMEDIAL LIABILITIES (Additional Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Environmental Remediation Obligations [Abstract]
Changes in estimates recorded to statement of income (loss)	$ 45	$ (1,635)
Future remediation liability	124,468	$ 128,007	$ 131,992
Possible increase in total remedial liabilities	$ 23,100
Accrual for environmental loss contingencies, threshold for disclosure (as a percent)	5.00%