SEGMENT REPORTING (Third Party Revenues to Direct Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 749,778	$ 688,941
Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0
Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	0	0
Direct revenues
Segment Reporting Information [Line Items]
Total revenues	749,778	688,941
Environmental Services
Segment Reporting Information [Line Items]
Total revenues	439,688	395,907
Environmental Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	31,965	32,069
Environmental Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	794	920
Environmental Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	472,447	428,896
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	309,918	292,901
Safety-Kleen | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(31,965)	(32,069)
Safety-Kleen | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	11	3
Safety-Kleen | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	277,964	260,835
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	172	133
Corporate Items | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0
Corporate Items | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(805)	(923)
Corporate Items | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	$ (633)	$ (790)