Geographical Information (Schedule of Revenue by Geographic Region) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenue by Geographic Region	$ 24,300	$ 17,219	$ 21,745	$ 24,001	$ 25,241	$ 17,717	$ 18,623	$ 24,036	$ 87,265	$ 85,617	$ 122,895
United States and Canada
Segment Reporting Information [Line Items]
Revenue by Geographic Region									68,607	69,543	98,520
Asia
Segment Reporting Information [Line Items]
Revenue by Geographic Region									11,637	10,386	16,713
Europe
Segment Reporting Information [Line Items]
Revenue by Geographic Region									6,209	5,422	7,015
Other
Segment Reporting Information [Line Items]
Revenue by Geographic Region									$ 812	$ 266	$ 647