REVENUES (Tables)

12 Months Ended

Dec. 31, 2022

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, 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

	For the year ended December 31, 2020
	Environmental Services		Safety-Kleen Sustainability Solutions		Corporate		Total
Primary Geographical Markets
United States	$	2,287,796	$	452,435	$	(674)	$	2,739,557
Canada	349,845		53,731		964		404,540
Total third-party revenues	$	2,637,641	$	506,166	$	290	$	3,144,097
Sources of Revenue
Technical Services	$	1,062,714	$	—	$	—	$	1,062,714
Industrial Services and Other	480,331		—		290		480,621
Field and Emergency Response Services	461,036		—		—		461,036
Safety-Kleen Environmental Services	633,560		175,676		—		809,236
Safety-Kleen Oil	—		330,490		—		330,490
Total third-party revenues	$	2,637,641	$	506,166	$	290	$	3,144,097

Schedule of Contract Balances

Contract Balances

(in thousands)	December 31, 2022		December 31, 2021
Receivables	$	964,603	$	792,734
Contract assets (unbilled receivables)	107,010		94,963
Contract liabilities (deferred revenue)	94,094		83,749