Segment Information - Reconciliation of Reportable Segment Operating Income (Loss) to Corresponding Consolidated Amounts (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Restructuring and other charges	$ 975	$ 1,475
Total operating income (loss)	13,161	(8,320)
Operating Segments
Segment Reporting Information [Line Items]
Total operating income (loss)	17,483	(1,662)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Amortization of acquired intangible assets	3,064	2,211
Restructuring and other charges	975	1,475
Other unallocated corporate expenses	$ 283	$ 2,972