Segment Information - Reconciliation of Reportable Segment Operating Income (Loss) to Corresponding Consolidated Amounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Amortization of acquired intangible assets	$ 5,500	$ 4,100
Restructuring Charges		975
Total operating income (loss)	20,840	13,161
Operating Segments
Segment Reporting Information [Line Items]
Total operating income (loss)	26,222	17,483
Segment Reconciling Items
Segment Reporting Information [Line Items]
Amortization of acquired intangible assets	4,589	3,064
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Other unallocated corporate expenses	$ 793	$ 283