Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 394,906	$ 384,612
Accumulated Amortization	176,581	133,444
Net Book Value	218,325	251,168
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	5,302	5,302
Accumulated Amortization	4,865	4,628
Net Book Value	437	674
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	92,477	88,288
Accumulated Amortization	49,875	38,778
Net Book Value	42,602	49,510
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	25,769	25,340
Accumulated Amortization	9,322	5,807
Net Book Value	16,447	19,533
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	271,113	265,451
Accumulated Amortization	112,277	84,048
Net Book Value	158,836	181,403
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Cost	245	231
Accumulated Amortization	242	183
Net Book Value	$ 3	$ 48