REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,459,537	$ 1,431,950
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	448,313	426,205
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	302,561	322,455
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	231,358	215,702
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	338,189	307,674
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	139,116	159,914
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,351,381	1,316,383
Canada
Disaggregation of Revenue [Line Items]
Total revenues	108,156	115,567
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,252,526	1,209,113
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	207,011	222,740
Operating Segments \| Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,242,448	1,207,038
Operating Segments \| Environmental Services \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	448,313	426,205
Operating Segments \| Environmental Services \| Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	302,561	322,358
Operating Segments \| Environmental Services \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	231,358	215,702
Operating Segments \| Environmental Services \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	260,216	242,773
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	1,151,108	1,116,267
Operating Segments \| Environmental Services \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	91,340	90,771
Operating Segments \| Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	217,089	224,815
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	77,973	64,901
Operating Segments \| Safety-Kleen Sustainability Solutions \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	139,116	159,914
Operating Segments \| Safety-Kleen Sustainability Solutions \| United States
Disaggregation of Revenue [Line Items]
Total revenues	200,273	200,019
Operating Segments \| Safety-Kleen Sustainability Solutions \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	16,816	24,796
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	0	97
Corporate \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate \| Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	0	97
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	0	97
Corporate \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0