Segment and Geographic Information - Reconciliation of Reportable Segment Operating Income and Segment Assets to Corresponding Consolidated Amounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Reconciliation
Segment operating income (loss)	$ 4,238	$ 16,890	$ (2,699)
Other unallocated corporate expenses	4,400	856	5,096
Amortization of acquired intangible assets	10,799	7,656	6,170
Restructuring and other charges	12,039	4,713	6,289
Operating income (loss)	4,238	16,890	(2,699)
Asset Reconciliation
Segment Assets	685,905	758,702
Cash, cash equivalents and marketable securities	91,221	214,030
Deferred tax assets	1,982	89,007
Assets held for sale	0	2,900
Equity method investments	27,250	24,286
Other unallocated corporate net assets	0	500
Total assets	685,905	758,702
Operating Segments, Total
Income Reconciliation
Segment operating income (loss)	31,476	30,115	14,856
Operating income (loss)	31,476	30,115	14,856
Asset Reconciliation
Segment Assets	565,452	427,979	415,120
Total assets	$ 565,452	$ 427,979	$ 415,120