REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,397,900	$ 1,356,312	$ 2,705,287	$ 2,525,421
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	389,908	387,019	756,417	710,675
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	399,661	360,949	736,147	669,859
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	154,359	144,860	302,445	277,219
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	280,122	241,138	539,689	461,471
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	173,850	222,346	370,589	406,197
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,254,849	1,182,537	2,435,311	2,219,817
Canada
Disaggregation of Revenue [Line Items]
Total revenues	143,051	173,775	269,976	305,604
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,172,036	1,090,743	2,242,777	2,038,188
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	225,748	265,490	462,287	487,082
Operating Segments | Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,161,482	1,084,506	2,222,464	2,025,304
Operating Segments | Environmental Services | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	389,908	387,019	756,417	710,675
Operating Segments | Environmental Services | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	399,545	360,870	735,924	669,708
Operating Segments | Environmental Services | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	154,359	144,860	302,445	277,219
Operating Segments | Environmental Services | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	217,670	191,757	427,678	367,702
Operating Segments | Environmental Services | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Environmental Services | United States
Disaggregation of Revenue [Line Items]
Total revenues	1,041,739	945,579	2,000,323	1,780,257
Operating Segments | Environmental Services | Canada
Disaggregation of Revenue [Line Items]
Total revenues	119,743	138,927	222,141	245,047
Operating Segments | Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	236,302	271,727	482,600	499,966
Operating Segments | Safety-Kleen Sustainability Solutions | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Safety-Kleen Sustainability Solutions | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Safety-Kleen Sustainability Solutions | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	62,452	49,381	112,011	93,769
Operating Segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	173,850	222,346	370,589	406,197
Operating Segments | Safety-Kleen Sustainability Solutions | United States
Disaggregation of Revenue [Line Items]
Total revenues	212,994	236,879	434,765	439,409
Operating Segments | Safety-Kleen Sustainability Solutions | Canada
Disaggregation of Revenue [Line Items]
Total revenues	23,308	34,848	47,835	60,557
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	116	79	223	151
Corporate | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	116	79	223	151
Corporate | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate | United States
Disaggregation of Revenue [Line Items]
Total revenues	116	79	223	151
Corporate | Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0