Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Cost	$ 198,175	$ 191,698
Accumulated Amortization	122,717	109,855
Net Book Value	75,458	81,843
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	9,028	7,808
Accumulated Amortization	7,724	7,486
Net Book Value	1,304	322
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	60,745	60,485
Accumulated Amortization	53,931	51,018
Net Book Value	6,814	9,467
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	9,142	9,142
Accumulated Amortization	4,776	4,204
Net Book Value	4,366	4,938
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	119,260	114,263
Accumulated Amortization	56,286	47,147
Net Book Value	$ 62,974	$ 67,116