Components of Identifiable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Sep. 30, 2011
Finite-Lived Intangible Assets [Line Items]
Cost	$ 115,411	$ 111,753
Accumulated Amortization	71,530	67,439
Net Book Value	43,881	44,314
Patents
Finite-Lived Intangible Assets [Line Items]
Cost	7,808	7,808
Accumulated Amortization	7,041	6,989
Net Book Value	767	819
Completed technology
Finite-Lived Intangible Assets [Line Items]
Cost	54,553	50,975
Accumulated Amortization	40,917	39,235
Net Book Value	13,636	11,740
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Cost	4,013	3,941
Accumulated Amortization	3,838	3,719
Net Book Value	175	222
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	49,037	49,029
Accumulated Amortization	19,734	17,496
Net Book Value	$ 29,303	$ 31,533