REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,365,696	$ 1,363,086	$ 4,070,983	$ 3,888,507
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	403,889	398,664	1,160,306	1,109,339
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	350,363	332,308	1,086,510	1,002,167
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	155,046	150,031	457,491	427,250
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	285,551	251,384	825,240	712,855
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	170,847	230,699	541,436	636,896
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,224,196	1,210,055	3,659,507	3,429,872
Canada
Disaggregation of Revenue [Line Items]
Total revenues	141,500	153,031	411,476	458,635
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,146,363	1,086,484	3,389,140	3,124,672
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	219,221	276,319	681,508	763,401
Operating Segments | Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,135,279	1,080,032	3,357,743	3,105,336
Operating Segments | Environmental Services | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	403,889	398,664	1,160,306	1,109,339
Operating Segments | Environmental Services | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	350,251	332,025	1,086,175	1,001,733
Operating Segments | Environmental Services | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	155,046	150,031	457,491	427,250
Operating Segments | Environmental Services | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	226,093	199,312	653,771	567,014
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	1,017,224	960,737	3,017,547	2,740,994
Operating Segments | Environmental Services | Canada
Disaggregation of Revenue [Line Items]
Total revenues	118,055	119,295	340,196	364,342
Operating Segments | Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	230,305	282,771	712,905	782,737
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	59,458	52,072	171,469	145,841
Operating Segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	170,847	230,699	541,436	636,896
Operating Segments | Safety-Kleen Sustainability Solutions | United States
Disaggregation of Revenue [Line Items]
Total revenues	206,860	249,035	641,625	688,444
Operating Segments | Safety-Kleen Sustainability Solutions | Canada
Disaggregation of Revenue [Line Items]
Total revenues	23,445	33,736	71,280	94,293
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	112	283	335	434
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	112	283	335	434
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	112	283	335	434
Corporate | Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0