Segment Information Reconciliation of Reportable Segment Operating Income (Loss) to Corresponding Consolidated Amounts (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other unallocated corporate expenses	$ 394	$ (2,934)	$ 1,284	$ (2,416)
Amortization of acquired intangible assets	1,413	1,138	2,965	2,355
Restructuring and other charges	769	42	5,526	245
In-process research and development	0	3,026	0	3,026
Operating income (loss)	(972)	8,415	(14,036)	9,878
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating income (loss)	$ 1,604	$ 9,687	$ (4,261)	$ 13,088