Goodwill and Other Intangible Assets - Summary of Gross Carrying Amounts and Accumulated Amortization of Intangible Assets by Major Class (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jun. 30, 2021	Sep. 30, 2020
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 202,545	$ 201,170
Accumulated Amortization	(171,927)	(155,554)
Net Carrying Amount	30,618	45,616
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	111,403	110,512
Accumulated Amortization	(86,165)	(75,915)
Net Carrying Amount	$ 25,238	$ 34,597
Weighted Average Remaining Life (Years)	2 years 4 months 24 days	3 years
Technology and Patents
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 91,142	$ 90,658
Accumulated Amortization	(85,762)	(79,639)
Net Carrying Amount	$ 5,380	$ 11,019
Weighted Average Remaining Life (Years)	1 year	1 year 7 months 6 days