Income and Other Taxes (Narrative) (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
Operating Loss Carryforwards [Line Items]
Income tax (expense) benefit	$ (10)	$ (14)	$ (15)	$ (15)	$ (53)	$ 0	$ 169	$ 333	$ (54)	$ 449	$ (163)
Effective tax rate on continuing operations									0.20%	(2.50%)	1.90%
Portion of operating loss carryforward subject to limitation	230,500								$ 230,500
Portion of operating loss carryforward not subject to limitation	242,300								242,300
Interest and penalties accrued as tax liabilities	500				$ 400				500	$ 400
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	472,800								472,800
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	5,100								5,100
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	71,200								71,200
Foreign Income And Research And Development Credit
Operating Loss Carryforwards [Line Items]
Tax credit	$ 2,700								$ 2,700