Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 391,740	$ 384,611
Accumulated Amortization	165,117	133,443
Net Book Value	226,623	251,168
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	8,251	5,302
Accumulated Amortization	5,013	4,628
Net Book Value	3,238	674
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	88,736	88,288
Accumulated Amortization	46,504	38,778
Net Book Value	42,232	49,510
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	25,604	25,340
Accumulated Amortization	8,425	5,807
Net Book Value	17,179	19,533
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	268,913	265,450
Accumulated Amortization	104,942	84,047
Net Book Value	163,971	181,403
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Cost	236	231
Accumulated Amortization	233	183
Net Book Value	$ 3	$ 48