Goodwill and Other Intangible Assets - Summary of Gross Carrying Amounts and Accumulated Amortization of Intangible Assets by Major Class (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2020	Sep. 30, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 197,671	$ 221,540
Accumulated Amortization	(142,564)	(155,979)
Net Carrying Amount	55,107	65,561
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	108,034	104,783
Accumulated Amortization	(67,887)	(58,568)
Net Carrying Amount	$ 40,147	$ 46,215
Weighted Average Remaining Life (Years)	3 years 4 months 24 days	4 years
Technology and Patents
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 89,637	$ 116,757
Accumulated Amortization	(74,677)	(97,411)
Net Carrying Amount	$ 14,960	$ 19,346
Weighted Average Remaining Life (Years)	2 years	2 years 6 months