INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Oil and oil products	$ 59,243	$ 58,142
Supplies and drums	97,246	94,242
Solvent and solutions	9,188	9,167
Modular camp accommodations	2,247	1,826
Other	13,514	12,635
Total inventories and supplies	$ 181,438	$ 176,012