INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Oil and oil products	$ 72,268	$ 58,142
Supplies and drums	99,773	94,242
Solvent and solutions	9,200	9,167
Modular camp accommodations	1,657	1,826
Other	13,147	12,635
Total inventories and supplies	$ 196,045	$ 176,012