SEGMENT REPORTING - Reconciliation of Third Party Revenues to Direct Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 1,397,900	$ 1,356,312	$ 2,705,287	$ 2,525,421
Environmental Services
Segment Reporting Information [Line Items]
Total revenues	1,172,036	1,090,743	2,242,777	2,038,188
Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Total revenues	225,748	265,490	462,287	487,082
Operating Segments | Environmental Services
Segment Reporting Information [Line Items]
Total revenues	1,161,482	1,084,506	2,222,464	2,025,304
Operating Segments | Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Total revenues	236,302	271,727	482,600	499,966
Intersegment Revenues (Expenses), net | Environmental Services
Segment Reporting Information [Line Items]
Total revenues	10,554	6,237	20,313	12,884
Intersegment Revenues (Expenses), net | Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Total revenues	(10,554)	(6,237)	(20,313)	(12,884)
Corporate
Segment Reporting Information [Line Items]
Total revenues	$ 116	$ 79	$ 223	$ 151