GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes to Goodwill

The changes in goodwill for the years ended December 31, 2021 and 2020 were as follows (in thousands):

	Environmental Services		Safety-Kleen Sustainability Solutions		Totals
Balance at January 1, 2020	$	401,680	$	123,333	$	525,013
Increase from current period acquisition	—		1,439		1,439
Measurement period adjustments from prior period acquisitions	23		—		23
Decrease from disposition of business	(674)		—		(674)
Foreign currency translation	889		333		1,222
Balance at December 31, 2020	$	401,918	$	125,105	$	527,023
Increase from current period acquisitions	683,463		16,349		699,812
Foreign currency translation	153		54		207
Balance at December 31, 2021	$	1,085,534	$	141,508	$	1,227,042

Schedule of Finite-Lived Intangible Assets by Major Class

As of December 31, 2021 and 2020, the Company's finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):

	December 31, 2021						December 31, 2020
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	187,519	$	102,408	$	85,111	$	183,766	$	95,033	$	88,733
Customer and supplier relationships	576,474		214,776		361,698		382,083		211,895		170,188
Other intangible assets	94,271		19,359		74,912		39,287		34,744		4,543
Total amortizable permits and other intangible assets	858,264		336,543		521,721		605,136		341,672		263,464
Trademarks and trade names	123,191		—		123,191		123,156		—		123,156
Total permits and other intangible assets	$	981,455	$	336,543	$	644,912	$	728,292	$	341,672	$	386,620

Schedule of Indefinite-Lived Intangible Assets

As of December 31, 2021 and 2020, the Company's finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):

	December 31, 2021						December 31, 2020
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	187,519	$	102,408	$	85,111	$	183,766	$	95,033	$	88,733
Customer and supplier relationships	576,474		214,776		361,698		382,083		211,895		170,188
Other intangible assets	94,271		19,359		74,912		39,287		34,744		4,543
Total amortizable permits and other intangible assets	858,264		336,543		521,721		605,136		341,672		263,464
Trademarks and trade names	123,191		—		123,191		123,156		—		123,156
Total permits and other intangible assets	$	981,455	$	336,543	$	644,912	$	728,292	$	341,672	$	386,620

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, 2021 is as follows (in thousands):

Years ending December 31,	Expected Amortization
2022	$	48,845
2023	44,595
2024	40,342
2025	38,485
2026	36,684
Thereafter	312,770
	$	521,721