REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,363,086	$ 951,479	$ 3,888,507	$ 2,686,085
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	398,664	308,158	1,109,339	887,063
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	150,031	116,677	427,250	328,831
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	332,308	155,036	1,002,167	425,371
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	251,384	203,570	712,855	597,790
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	230,699	168,038	636,896	447,030
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,210,055	817,910	3,429,872	2,329,367
Canada
Disaggregation of Revenue [Line Items]
Total revenues	153,031	133,569	458,635	356,718
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,086,484	745,633	3,124,672	2,124,332
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	276,319	205,787	763,401	561,536
Operating segments | Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,080,032	743,831	3,105,336	2,119,856
Operating segments | Environmental Services | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	398,664	308,158	1,109,339	887,063
Operating segments | Environmental Services | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	150,031	116,677	427,250	328,831
Operating segments | Environmental Services | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	332,025	154,977	1,001,733	425,154
Operating segments | Environmental Services | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	199,312	164,019	567,014	478,808
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	960,737	632,755	2,740,994	1,824,848
Operating segments | Environmental Services | Canada
Disaggregation of Revenue [Line Items]
Total revenues	119,295	111,076	364,342	295,008
Operating segments | Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	282,771	207,589	782,737	566,012
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 | Field and Emergency Response 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 | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	52,072	39,551	145,841	118,982
Operating segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	230,699	168,038	636,896	447,030
Operating segments | Safety-Kleen Sustainability Solutions | United States
Disaggregation of Revenue [Line Items]
Total revenues	249,035	185,096	688,444	504,302
Operating segments | Safety-Kleen Sustainability Solutions | Canada
Disaggregation of Revenue [Line Items]
Total revenues	33,736	22,493	94,293	61,710
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	283	59	434	217
Corporate | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	283	59	434	217
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	283	59	434	217
Corporate | Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0