Goodwill and Other Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 122,731	$ 86,308
Accumulated amortization	(80,953)	(74,508)
Net	41,778	11,800
Purchased and Core Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	58,048	51,292
Accumulated amortization	(47,983)	(46,304)
Net	10,065	4,988
License Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	102	18
Accumulated amortization	(39)	(17)
Net	63	1
Patents and Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	15,612	12,484
Accumulated amortization	(11,965)	(11,280)
Net	3,647	1,204
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	46,569	21,914
Accumulated amortization	(19,886)	(16,817)
Net	26,683	5,097
Non-compete Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	600	600
Accumulated amortization	(180)	(90)
Net	420	510
Order backlog
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,800	0
Accumulated amortization	(900)	0
Net	$ 900	$ 0