Fair Value Measurements (Contingent Consideration Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Contingent consideration, beginning balance	$ 8,400	$ 19,570
Contingent consideration at acquisition	2,100
Change in fair value of contingent consideration		930
Payment of contingent consideration	(8,925)	(12,100)
Contingent consideration, ending balance	1,575	8,400
ColdLight [Member]
Business Acquisition [Line Items]
Contingent consideration, beginning balance	0	2,500
Contingent consideration at acquisition	0
Change in fair value of contingent consideration		0
Payment of contingent consideration	0	(2,500)
Contingent consideration, ending balance	0	0
Kepware [Member]
Business Acquisition [Line Items]
Contingent consideration, beginning balance	8,400	17,070
Contingent consideration at acquisition	0
Change in fair value of contingent consideration		930
Payment of contingent consideration	(8,400)	(9,600)
Contingent consideration, ending balance	0	8,400
Other [Member]
Business Acquisition [Line Items]
Contingent consideration, beginning balance	0	0
Contingent consideration at acquisition	2,100
Change in fair value of contingent consideration		0
Payment of contingent consideration	(525)	0
Contingent consideration, ending balance	$ 1,575	$ 0