SEGMENT REPORTING - Reconciliation to Consolidated Statements of Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 1,012,570	$ 1,022,128	$ 676,606
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	13,667	12,943	11,745
Stock-based compensation	20,703	26,844	18,839
Depreciation and amortization	365,761	347,594	298,135
Income from operations	612,439	634,747	347,887
Other Nonoperating Income (Expense)	(2,315)	(2,472)	515
Loss on early extinguishment of debt	2,880	422	0
Gain on sale of business	0	(8,864)	0
Interest expense, net of interest income	108,595	107,663	77,657
Income from operations before provision for income taxes	503,279	537,998	269,715
Operating segments | Environmental Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	1,101,608	953,053	659,718
Operating segments | Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Adjusted EBITDA	172,873	306,327	227,354
Corporate, non-segment
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (261,911)	$ (237,252)	$ (210,466)