Income and Other Taxes (Provision for Income Taxes) (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
Income Tax Disclosure [Abstract]
Income tax (benefit) expense computed at U.S. federal statutory rate									$ (7,540)	$ (4,346)	$ 2,841
State tax expense benefit, net of U.S. federal effect									(906)	(168)	414
Foreign tax rate differential									(28)	36	229
Effect due to change in tax rate									(183)	57,988	2,528
Shortfall (windfall) from stock based compensation									248	681	(150)
Other									223	216	126
State net operating loss carryforward adjustment									139	(305)	933
Change in valuation allowance									8,101	(54,551)	(6,758)
Total income tax (benefit) expense	$ 10	$ 14	$ 15	$ 15	$ 53	$ 0	$ (169)	$ (333)	$ 54	$ (449)	$ 163
Effective tax rate (percentage)									0.20%	(2.50%)	1.90%