REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,376,695	$ 1,307,387
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	407,491	366,509
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	359,499	336,486
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	163,469	148,086
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	283,943	259,567
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	162,293	196,739
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,247,472	1,180,462
Canada
Disaggregation of Revenue [Line Items]
Total revenues	129,223	126,925
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,172,510	1,070,741
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	204,083	236,539
Operating Segments | Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,161,279	1,060,982
Operating Segments | Environmental Services | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	407,491	366,509
Operating Segments | Environmental Services | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	359,397	336,379
Operating Segments | Environmental Services | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	163,469	148,086
Operating Segments | Environmental Services | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	230,922	210,008
Operating Segments | Environmental Services | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | Environmental Services | United States
Disaggregation of Revenue [Line Items]
Total revenues	1,053,458	958,584
Operating Segments | Environmental Services | Canada
Disaggregation of Revenue [Line Items]
Total revenues	107,821	102,398
Operating Segments | Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	215,314	246,298
Operating Segments | Safety-Kleen Sustainability Solutions | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | Safety-Kleen Sustainability Solutions | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | Safety-Kleen Sustainability Solutions | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Operating Segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	53,021	49,559
Operating Segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	162,293	196,739
Operating Segments | Safety-Kleen Sustainability Solutions | United States
Disaggregation of Revenue [Line Items]
Total revenues	193,912	221,771
Operating Segments | Safety-Kleen Sustainability Solutions | Canada
Disaggregation of Revenue [Line Items]
Total revenues	21,402	24,527
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	102	107
Corporate | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	102	107
Corporate | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate | United States
Disaggregation of Revenue [Line Items]
Total revenues	102	107
Corporate | Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0