Goodwill and Other Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 122,503			$ 122,910
Accumulated amortization	(85,731)			(83,590)
Net	36,772			39,320	[1]
Amortization expense	2,540	$ 1,694	[1]
Purchased and Core Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	57,821			58,102
Accumulated amortization	(49,113)			(48,693)
Net	8,708			9,409
License Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	102			102
Accumulated amortization	(53)			(46)
Net	49			56
Patents and Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	15,748			15,701
Accumulated amortization	(12,501)			(12,242)
Net	3,247			3,459
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	46,432			46,605
Accumulated amortization	(22,024)			(21,049)
Net	24,408			25,556
Non-compete Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	600			600
Accumulated amortization	(240)			(210)
Net	360			390
Order backlog
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,800			1,800
Accumulated amortization	(1,800)			(1,350)
Net	0			$ 450
Cost of Sales and General and Administrative Expense
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 2,500	$ 1,700

[1] Prior period information has been restated for the adoption of ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which we adopted on October 1, 2018.