REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenues	$ 6,030,837	$ 5,889,952	$ 5,409,152
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	1,859,705	1,733,550	1,563,847
Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	1,328,069	1,377,909	1,419,385
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	937,362	895,120	609,913
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,311,827	1,183,883	1,102,041
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	593,874	699,490	713,966
United States
Disaggregation of Revenue [Line Items]
Total revenues	5,490,884	5,352,423	4,869,180
Canada
Disaggregation of Revenue [Line Items]
Total revenues	539,953	537,529	539,972
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	5,193,290	5,004,747	4,511,442
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	837,361	884,798	897,263
Operating segments \| Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	5,146,354	4,960,325	4,469,909
Operating segments \| Environmental Services \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	1,859,705	1,733,550	1,563,847
Operating segments \| Environmental Services \| Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	1,327,883	1,377,502	1,418,938
Operating segments \| Environmental Services \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	937,362	895,120	609,913
Operating segments \| Environmental Services \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,021,404	954,153	877,211
Operating segments \| Environmental Services \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Operating segments \| Environmental Services \| United States
Disaggregation of Revenue [Line Items]
Total revenues	4,705,709	4,510,845	4,022,394
Operating segments \| Environmental Services \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	440,645	449,480	447,515
Operating segments \| Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	884,297	929,220	938,796
Operating segments \| Safety-Kleen Sustainability Solutions \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Operating segments \| Safety-Kleen Sustainability Solutions \| Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Operating segments \| Safety-Kleen Sustainability Solutions \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Operating segments \| Safety-Kleen Sustainability Solutions \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	290,423	229,730	224,830
Operating segments \| Safety-Kleen Sustainability Solutions \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	593,874	699,490	713,966
Operating segments \| Safety-Kleen Sustainability Solutions \| United States
Disaggregation of Revenue [Line Items]
Total revenues	784,989	841,171	846,339
Operating segments \| Safety-Kleen Sustainability Solutions \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	99,308	88,049	92,457
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	186	407	447
Corporate \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate \| Industrial Services and Other
Disaggregation of Revenue [Line Items]
Total revenues	186	407	447
Corporate \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate \| United States
Disaggregation of Revenue [Line Items]
Total revenues	186	407	447
Corporate \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0