SEGMENT REPORTING - Reconciliation of Third Party Revenues to Direct Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 1,307,387	$ 1,169,109
Environmental Services
Segment Reporting Information [Line Items]
Total revenues	1,070,741	947,445
Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Total revenues	236,539	221,592
Operating Segments | Environmental Services
Segment Reporting Information [Line Items]
Total revenues	1,060,982	940,798
Operating Segments | Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Total revenues	246,298	228,239
Intersegment Revenues (Expenses), net | Environmental Services
Segment Reporting Information [Line Items]
Total revenues	9,759	6,647
Intersegment Revenues (Expenses), net | Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Total revenues	(9,759)	(6,647)
Corporate
Segment Reporting Information [Line Items]
Total revenues	$ 107	$ 72