REVENUES (Tables)

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

The following tables present the Company's third-party revenue disaggregated by source of revenue and geography (in thousands):

	For the year ended December 31, 2023
	Environmental Services		Safety-Kleen Sustainability Solutions		Corporate		Total
Primary Geographical Markets
United States	$	4,022,394	$	846,339	$	447	$	4,869,180
Canada	447,515		92,457		—		539,972
Total third-party revenues	$	4,469,909	$	938,796	$	447	$	5,409,152
Sources of Revenue
Technical Services	$	1,563,847	$	—	$	—	$	1,563,847
Industrial Services and Other	1,418,938		—		447		1,419,385
Field and Emergency Response Services	609,913		—		—		609,913
Safety-Kleen Environmental Services	877,211		224,830		—		1,102,041
Safety-Kleen Oil	—		713,966		—		713,966
Total third-party revenues	$	4,469,909	$	938,796	$	447	$	5,409,152

	For the year ended December 31, 2022
	Environmental Services		Safety-Kleen Sustainability Solutions		Corporate		Total
Primary Geographical Markets
United States	$	3,675,880	$	899,780	$	507	$	4,576,167
Canada	469,093		121,345		—		590,438
Total third-party revenues	$	4,144,973	$	1,021,125	$	507	$	5,166,605
Sources of Revenue
Technical Services	$	1,495,264	$	—	$	—	$	1,495,264
Industrial Services and Other	1,311,072		—		507		1,311,579
Field and Emergency Response Services	575,300		—		—		575,300
Safety-Kleen Environmental Services	763,337		199,360		—		962,697
Safety-Kleen Oil	—		821,765		—		821,765
Total third-party revenues	$	4,144,973	$	1,021,125	$	507	$	5,166,605

	For the year ended December 31, 2021
	Environmental Services		Safety-Kleen Sustainability Solutions		Corporate		Total
Primary Geographical Markets
United States	$	2,631,112	$	693,542	$	299	$	3,324,953
Canada	394,795		85,818		—		480,613
Total third-party revenues	$	3,025,907	$	779,360	$	299	$	3,805,566
Sources of Revenue
Technical Services	$	1,209,624	$	—	$	—	$	1,209,624
Industrial Services and Other	705,999		—		299		706,298
Field and Emergency Response Services	466,380		—		—		466,380
Safety-Kleen Environmental Services	643,904		161,587		—		805,491
Safety-Kleen Oil	—		617,773		—		617,773
Total third-party revenues	$	3,025,907	$	779,360	$	299	$	3,805,566

Schedule of Contract Balances

Contract Balances

(in thousands)	December 31, 2023		December 31, 2022
Receivables	$	983,111	$	964,603
Contract assets (unbilled receivables)	107,859		107,010
Contract liabilities (deferred revenue)	95,230		94,094