SEGMENT REPORTING - Adjusted EBITDA and Significant Segment Expense Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Segment Reporting Information [Line Items]
Direct Revenues	$ 1,459,537	$ 1,431,950
Cost of Revenues	1,014,120	1,021,884
Selling, General and Administrative Expenses	207,141	182,847
Total Reportable Segments
Segment Reporting Information [Line Items]
Direct Revenues	1,459,537	1,431,853
Cost of Revenues	1,007,016	1,017,380
Selling, General and Administrative Expenses	129,139	111,630
Total Reportable Segment Adjusted EBITDA	323,382	302,843
Environmental Services
Segment Reporting Information [Line Items]
Direct Revenues	1,252,526	1,209,113
Cost of Revenues	852,380	839,942
Selling, General and Administrative Expenses	109,745	94,580
Total Reportable Segment Adjusted EBITDA	290,401	274,591
Safety-Kleen Sustainability Solutions
Segment Reporting Information [Line Items]
Direct Revenues	207,011	222,740
Cost of Revenues	154,636	177,438
Selling, General and Administrative Expenses	19,394	17,050
Total Reportable Segment Adjusted EBITDA	$ 32,981	$ 28,252

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

- Definition

The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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