GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2024

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes to Goodwill

The changes in goodwill for the years ended December 31, 2024 and 2023 were as follows (in thousands):

	Environmental Services		Safety-Kleen Sustainability Solutions		Total
Balance at January 1, 2023	$	1,071,846	$	175,032	$	1,246,878
Increase from current period acquisitions	39,346		—		39,346
Measurement period adjustments from prior period acquisition	—		360		360
Foreign currency translation	821		331		1,152
Balance at December 31, 2023	$	1,112,013	$	175,723	$	1,287,736
Increase from current period acquisitions	186,911		6,457		193,368
Measurement period adjustments from prior period acquisitions	218		—		218
Foreign currency translation	(2,938)		(1,185)		(4,123)
Balance at December 31, 2024	$	1,296,204	$	180,995	$	1,477,199

Schedule of Finite-Lived Intangible Assets by Major Class

As of December 31, 2024 and 2023, the Company's intangible assets consisted of the following (in thousands):

	December 31, 2024						December 31, 2023
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	191,921	$	123,939	$	67,982	$	191,747	$	117,556	$	74,191
Customer and supplier relationships	697,326		256,657		440,669		604,994		258,879		346,115
Other intangible assets	120,316		46,490		73,826		100,068		37,862		62,206
Total amortizable permits and other intangible assets	1,009,563		427,086		582,477		896,809		414,297		482,512
Trademarks and trade names	119,510		—		119,510		120,285		—		120,285
Total permits and other intangible assets	$	1,129,073	$	427,086	$	701,987	$	1,017,094	$	414,297	$	602,797

Schedule of Indefinite-Lived Intangible Assets

As of December 31, 2024 and 2023, the Company's intangible assets consisted of the following (in thousands):

	December 31, 2024						December 31, 2023
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	191,921	$	123,939	$	67,982	$	191,747	$	117,556	$	74,191
Customer and supplier relationships	697,326		256,657		440,669		604,994		258,879		346,115
Other intangible assets	120,316		46,490		73,826		100,068		37,862		62,206
Total amortizable permits and other intangible assets	1,009,563		427,086		582,477		896,809		414,297		482,512
Trademarks and trade names	119,510		—		119,510		120,285		—		120,285
Total permits and other intangible assets	$	1,129,073	$	427,086	$	701,987	$	1,017,094	$	414,297	$	602,797

Schedule of Expected Amortization for the Net Carrying Amount of Finite Lived Intangible Assets

The expected amortization of the net carrying amount of finite-lived intangible assets at December 31, 2024 was as follows (in thousands):

Years ending December 31,	Expected Amortization
2025	$	53,335
2026	51,297
2027	49,221
2028	47,916
2029	46,763
Thereafter	333,945
	$	582,477