Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation before income taxes	$ 4,659	$ 3,649	$ 3,881
Income tax benefit	(1,536)	(1,185)	(1,343)
Stock-based compensation after income taxes	3,123	2,464	2,538
Cost of Sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation before income taxes	213	215	221
Sales and Marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation before income taxes	1,348	921	1,158
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation before income taxes	656	590	561
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation before income taxes	$ 2,442	$ 1,923	$ 1,941