Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Cost	$ 384,612	$ 198,918
Accumulated Amortization	133,444	98,962
Net Book Value	251,168	99,956
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	5,302	5,302
Accumulated Amortization	4,628	4,325
Net Book Value	674	977
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	88,288	44,829
Accumulated Amortization	38,778	28,934
Net Book Value	49,510	15,895
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	25,340	6,298
Accumulated Amortization	5,807	2,953
Net Book Value	19,533	3,345
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	265,451	142,489
Accumulated Amortization	84,048	62,750
Net Book Value	181,403	$ 79,739
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Cost	231
Accumulated Amortization	183
Net Book Value	$ 48