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, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Amortization of acquired intangible assets	$ 1,914	$ 1,460	$ 3,826	$ 2,916
Restructuring and other charges	685	772	3,353	1,519
Other unallocated corporate expenses	60	182	459	217
Operating income (loss)	3,053	2,396	(3,427)	3,854
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating income (loss)	$ 5,712	$ 4,810	$ 4,211	$ 8,506