The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Goodwill and Other Intangible Assets - Additional information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization expense related to intangible assets		$ 19,488,000	$ 18,328,000	$ 16,338,000
Asset Impairment Charges	$ 0	0
Estimated intangibel asset amortization for 2020	22,000,000	22,000,000
Estimated intangibel asset amortization for 2021	22,000,000	22,000,000
Estimated intangibel asset amortization for 2022	22,000,000	22,000,000
Estimated intangibel asset amortization for 2023	22,000,000	22,000,000
Estimated intangibel asset amortization for 2024	$ 22,000,000	$ 22,000,000
Customer relationships \| Maximum
Finite-Lived Intangible Assets [Line Items]
Expected remaining useful life		20 years
Customer relationships \| Minimum
Finite-Lived Intangible Assets [Line Items]
Expected remaining useful life		15 years
Patents
Finite-Lived Intangible Assets [Line Items]
Expected remaining useful life		17 years
Capitalized software \| Maximum
Finite-Lived Intangible Assets [Line Items]
Expected remaining useful life		7 years
Capitalized software \| Minimum
Finite-Lived Intangible Assets [Line Items]
Expected remaining useful life		3 years