Goodwill and Other Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 123,503	$ 86,308
Accumulated amortization	(79,202)	(74,508)
Net	44,301	11,800
Purchased and Core Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	58,541	51,292
Accumulated amortization	(47,787)	(46,304)
Net	10,754	4,988
License Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	102	18
Accumulated amortization	(32)	(17)
Net	70	1
Patents and Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	15,542	12,484
Accumulated amortization	(11,701)	(11,280)
Net	3,841	1,204
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	46,918	21,914
Accumulated amortization	(19,082)	(16,817)
Net	27,836	5,097
Non-compete Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	600	600
Accumulated amortization	(150)	(90)
Net	450	510
Order backlog
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,800	0
Accumulated amortization	(450)	0
Net	$ 1,350	$ 0