GOODWILL AND OTHER INTANGIBLE ASSETS - Changes to Goodwill (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 1,227,042
Increase from current period acquisition	29,375
Measurement period adjustments from prior period acquisition	(6,453)
Decrease from disposition of business	(4,412)
Foreign currency translation	(897)
Goodwill, ending balance	1,244,655
Environmental Services
Goodwill [Roll Forward]
Goodwill, beginning balance	1,085,534
Increase from current period acquisition	0
Measurement period adjustments from prior period acquisition	(6,453)
Decrease from disposition of business	(4,412)
Foreign currency translation	(659)
Goodwill, ending balance	1,074,010
Safety-Kleen Sustainability Solutions
Goodwill [Roll Forward]
Goodwill, beginning balance	141,508
Increase from current period acquisition	29,375
Measurement period adjustments from prior period acquisition	0
Decrease from disposition of business	0
Foreign currency translation	(238)
Goodwill, ending balance	$ 170,645