Goodwill and Intangible Assets - Components of Identifiable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Finite-Lived Intangible Assets [Line Items]
Cost	$ 141,848	$ 135,109
Accumulated Amortization	82,298	75,021
Net Book Value	59,550	60,088
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	7,808	7,808
Accumulated Amortization	7,300	7,196
Net Book Value	508	612
Completed technology
Finite-Lived Intangible Assets [Line Items]
Cost	57,155	57,050
Accumulated Amortization	41,539	40,354
Net Book Value	15,616	16,696
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Cost	3,496	3,564
Accumulated Amortization	3,496	3,554
Net Book Value	0	10
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	73,389	66,687
Accumulated Amortization	29,963	23,917
Net Book Value	$ 43,426	$ 42,770