GOODWILL AND OTHER INTANGIBLE ASSETS - Changes to Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 1,246,878
Increase from current period acquisition	39,088
Measurement period adjustments from prior period acquisitions	342
Foreign currency translation	165
Goodwill, ending balance	1,286,473
Environmental Services
Goodwill [Roll Forward]
Goodwill, beginning balance	1,071,846
Increase from current period acquisition	39,088
Measurement period adjustments from prior period acquisitions	0
Foreign currency translation	118
Goodwill, ending balance	1,111,052
Safety-Kleen Sustainability Solutions
Goodwill [Roll Forward]
Goodwill, beginning balance	175,032
Increase from current period acquisition	0
Measurement period adjustments from prior period acquisitions	342
Foreign currency translation	47
Goodwill, ending balance	$ 175,421