Components of Identifiable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Sep. 30, 2011
Finite-Lived Intangible Assets [Line Items]
Cost	$ 114,981	$ 111,753
Accumulated Amortization	69,434	67,439
Net Book Value	45,547	44,314
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	7,808	7,808
Accumulated Amortization	7,015	6,989
Net Book Value	793	819
Completed technology
Finite-Lived Intangible Assets [Line Items]
Cost	54,527	50,975
Accumulated Amortization	40,001	39,235
Net Book Value	14,526	11,740
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Cost	4,012	3,941
Accumulated Amortization	3,817	3,719
Net Book Value	195	222
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	48,634	49,029
Accumulated Amortization	18,601	17,496
Net Book Value	$ 30,033	$ 31,533