OTHER NON-CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other Liabilities, Noncurrent [Abstract]
Long-term lease liabilities (see Note 9)	$ 119,323	$ 0
Accrued employee benefit liabilities	27,632	28,246
Accrued environmental remediation liabilities	23,541	27,358
Deferred consideration	29,216	20,232
Asset retirement obligations	4,337	4,349
Other	7,215	4,715
Total other non-current liabilities	$ 211,264	$ 84,900