Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Cost	$ 191,698	$ 150,513
Accumulated Amortization	109,855	95,067
Net Book Value	81,843	55,446
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	7,808	7,808
Accumulated Amortization	7,486	7,394
Net Book Value	322	414
Completed technology
Finite-Lived Intangible Assets [Line Items]
Cost	60,485	60,748
Accumulated Amortization	51,018	46,718
Net Book Value	9,467	14,030
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Cost	9,142	4,241
Accumulated Amortization	4,204	3,604
Net Book Value	4,938	637
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	114,263	77,716
Accumulated Amortization	47,147	37,351
Net Book Value	$ 67,116	$ 40,365