INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Oil and oil related products	$ 70,823	$ 58,142
Supplies and drums	104,609	94,242
Solvent and solutions	10,657	9,167
Modular camp accommodations	0	1,826
Other	13,390	12,635
Total inventories and supplies	199,479	176,012
Transfer of inventory to property, plant and equipment	$ 0	$ 12,641	$ 0