Income and Other Taxes (Provision for Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income tax benefit computed at U.S. federal statutory rate									$ (4,346)	$ 2,841	$ 896
State tax expense benefit, net of U.S. federal effect									(168)	414	(41)
Foreign tax rate differential									36	229	(94)
Effect due to change in tax rate									57,988	2,528	626
Shortfall (windfall) from stock based compensation									681	(150)	0
Other									216	126	(57)
State net operating loss carryforward adjustment									(305)	933	685
Change in valuation allowance									(54,551)	(6,758)	(2,001)
Total income tax (benefit) expense	$ 53	$ 0	$ (169)	$ (333)	$ 32	$ 19	$ (8)	$ 120	$ (449)	$ 163	$ 14
Effective tax rate									(2.50%)	1.90%	0.50%