REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,431,950	$ 1,376,695
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	426,205	407,491
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	322,455	359,499
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	215,702	163,469
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	307,674	283,943
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	159,914	162,293
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,316,383	1,247,472
Canada
Disaggregation of Revenue [Line Items]
Total revenues	115,567	129,223
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,209,113	1,172,510
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	222,740	204,083
Operating Segments | Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,207,038	1,161,279
Operating Segments | Environmental Services | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	426,205	407,491
Operating Segments | Environmental Services | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	322,358	359,397
Operating Segments | Environmental Services | Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	215,702	163,469
Operating Segments | Environmental Services | Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	242,773	230,922
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	1,116,267	1,053,458
Operating Segments | Environmental Services | Canada
Disaggregation of Revenue [Line Items]
Total revenues	90,771	107,821
Operating Segments | Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	224,815	215,314
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	64,901	53,021
Operating Segments | Safety-Kleen Sustainability Solutions | Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	159,914	162,293
Operating Segments | Safety-Kleen Sustainability Solutions | United States
Disaggregation of Revenue [Line Items]
Total revenues	200,019	193,912
Operating Segments | Safety-Kleen Sustainability Solutions | Canada
Disaggregation of Revenue [Line Items]
Total revenues	24,796	21,402
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	97	102
Corporate | Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate | Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	97	102
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	97	102
Corporate | Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0