Goodwill and Intangible Assets Components of Identifiable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Finite-Lived Intangible Assets [Line Items]
Cost	$ 145,372	$ 115,059
Accumulated Amortization	80,796	75,659
Net Book Value	64,576	39,400
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	7,808	7,808
Accumulated Amortization	7,145	7,093
Net Book Value	663	715
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Cost	65,018	54,583
Accumulated Amortization	44,905	42,751
Net Book Value	20,113	11,832
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Cost	4,010	4,014
Accumulated Amortization	3,918	3,880
Net Book Value	92	134
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Cost	68,536	48,654
Accumulated Amortization	24,828	21,935
Net Book Value	$ 43,708	$ 26,719