Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 390,303	$ 384,611
Accumulated Amortization	154,208	133,443
Net Book Value	236,095	251,168
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	8,251	5,302
Accumulated Amortization	4,833	4,628
Net Book Value	3,418	674
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	88,309	88,288
Accumulated Amortization	43,946	38,778
Net Book Value	44,363	49,510
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	25,591	25,340
Accumulated Amortization	7,543	5,807
Net Book Value	18,048	19,533
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	267,921	265,450
Accumulated Amortization	97,665	84,047
Net Book Value	170,256	181,403
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Cost	231	231
Accumulated Amortization	221	183
Net Book Value	$ 10	$ 48