SEGMENT REPORTING - Reconciliation to Consolidated Statements of Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 255,017		$ 308,555	$ 757,661	$ 797,884
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	3,388		3,246	10,281	9,599
Stock-based compensation	4,291		7,828	14,809	20,375
Depreciation and amortization	92,970		88,394	267,425	260,560
Income from operations	154,368		209,087	465,146	507,350
Other (income) expense, net	(334)		(104)	833	(2,073)
Loss on early extinguishment of debt	0	$ 2,400	0	2,362	0
Gain on sale of business	0		0	0	(8,864)
Interest expense, net of interest income	29,696		28,081	80,400	79,354
Income before provision for income taxes	125,006		181,110	381,551	438,933
Operating Segments | Environmental Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	288,982		260,687	822,949	713,630
Operating Segments | Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Adjusted EBITDA	31,146		103,156	126,024	252,043
Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (65,111)		$ (55,288)	$ (191,312)	$ (167,789)