REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,549,337	$ 1,529,422	$ 4,531,141	$ 4,458,836
Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	490,768	437,180	1,380,394	1,288,339
Industrial Services
Disaggregation of Revenue [Line Items]
Total revenues	332,102	345,669	1,016,226	1,064,738
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	232,262	260,200	690,755	676,562
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	340,049	304,372	982,453	888,002
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	154,156	182,001	461,313	541,195
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,396,783	1,385,719	4,116,135	4,041,407
Canada
Disaggregation of Revenue [Line Items]
Total revenues	152,554	143,703	415,006	417,429
Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,331,300	1,297,187	3,892,448	3,779,080
Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	218,037	232,139	638,507	679,459
Operating Segments \| Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	1,318,580	1,287,650	3,855,677	3,746,227
Operating Segments \| Environmental Services \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	490,768	437,180	1,380,394	1,288,339
Operating Segments \| Environmental Services \| Industrial Services
Disaggregation of Revenue [Line Items]
Total revenues	332,102	345,573	1,016,040	1,064,441
Operating Segments \| Environmental Services \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	232,262	260,200	690,755	676,562
Operating Segments \| Environmental Services \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	263,448	244,697	768,488	716,885
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	1,194,300	1,166,660	3,519,337	3,395,446
Operating Segments \| Environmental Services \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	124,280	120,990	336,340	350,781
Operating Segments \| Safety-Kleen Sustainability Solutions
Disaggregation of Revenue [Line Items]
Total revenues	230,757	241,676	675,278	712,312
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 \| Industrial 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 \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total revenues	76,601	59,675	213,965	171,117
Operating Segments \| Safety-Kleen Sustainability Solutions \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total revenues	154,156	182,001	461,313	541,195
Operating Segments \| Safety-Kleen Sustainability Solutions \| United States
Disaggregation of Revenue [Line Items]
Total revenues	202,483	218,963	596,612	645,664
Operating Segments \| Safety-Kleen Sustainability Solutions \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	28,274	22,713	78,666	66,648
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	0	96	186	297
Corporate \| Technical Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Corporate \| Industrial Services
Disaggregation of Revenue [Line Items]
Total revenues	0	96	186	297
Corporate \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
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	0	96	186	297
Corporate \| Canada
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0