SEGMENT REPORTING (Third Party Revenues to Direct Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 780,839	$ 749,778
Direct revenues
Segment Reporting Information [Line Items]
Total revenues	780,839	749,778
Environmental Services
Segment Reporting Information [Line Items]
Total revenues	473,698	439,688
Environmental Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	34,075	31,965
Environmental Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	1,249	794
Environmental Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	509,022	472,447
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	306,547	309,918
Safety-Kleen | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(34,075)	(31,965)
Safety-Kleen | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	5	11
Safety-Kleen | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	272,477	277,964
Corporate
Segment Reporting Information [Line Items]
Total revenues	594	172
Corporate | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(1,254)	(805)
Corporate | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	$ (660)	$ (633)