Other Intangible Assets

12 Months Ended

Sep. 30, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets consist of the following:


		September 30, 2021
	Estimated Life (years)	Carrying Amount		Accumulated Amortization		Net
Amortizing intangible assets
Customer related	5 - 26	$	300,963	$	(101,272)	$	199,691
Proprietary technology	7 - 10	61,692		(36,921)		$	24,771
Trademark	5 - 15	27,195		(12,191)		$	15,004
Backlog	1	82,355		(82,355)		$	—
Other	3 - 10	47,903		(31,501)		$	16,402
Total amortizing intangible assets		$	520,108	$	(264,240)	$	255,868
Indefinite‑lived intangible assets		34,207		—		$	34,207
Total intangible assets		$	554,315	$	(264,240)	$	290,075


		September 30, 2020
	Estimated Life (years)	Carrying Amount		Accumulated Amortization		Net
Amortizing intangible assets
Customer related	5 - 26	$	292,316	$	(83,486)	$	208,830
Proprietary technology	7 - 10	61,990		(30,886)		$	31,104
Trademark	5 - 15	27,114		(9,142)		$	17,972
Backlog	1	82,181		(82,181)		$	—
Other	3	39,010		(21,156)		$	17,854
Total amortizing intangible assets		$	502,611	$	(226,851)	$	275,760
Indefinite‑lived intangible assets		34,207		—		$	34,207
Total intangible assets		$	536,818	$	(226,851)	$	309,967

The Company’s indefinite-lived intangible asset relate to Federal hazardous waste treatment management permits obtained for locations operated by the Integrated Solutions and Services segment. The permits are considered perpetually renewable. The Company performs an indefinite-lived intangible asset impairment analysis on an annual basis during the fourth quarter of the year and whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The Company assessed the carrying value of the permits at the Integrated Solutions and Services segment as of July 1, 2021 using a quantitative analysis outlined in ASU No. 2012-02 to determine whether the existence of events or circumstances would lead to the conclusion that it is more likely than not that the fair values of the permits are less than the carrying amounts. Events and circumstances considered in this review included macroeconomic conditions, new competition, financial performance of the entities which utilizes the permits and other financial and non-financial events. Based on these factors, the Company concluded the fair value of the permits were not more likely than not less than the carrying amounts.

For the amortizing intangible assets, the remaining weighted-average amortization period at September 30, 2021 was as follows:


			Years
Customer-related intangibles			9
Proprietary technology			4
Trademarks			6
Other			2
Aggregate net intangible assets			6

Intangible asset amortization was $37,385, $34,266, and $32,205 for the years ended September 30, 2021, 2020 and 2019, respectively. The estimated future amortization expense is as follows:



2022	$	36,702
2023	33,086
2024	27,616
2025	22,703
2026	19,904
Thereafter	115,857
Total	$	255,868