Income and Other Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 572	$ 60	$ 54
Effective tax rate on continuing operations	2.20%	0.90%	0.20%
Portion of operating loss carryforward subject to limitation	$ 230,200
Portion of operating loss carryforward not subject to limitation	228,300
Interest and penalties accrued as tax liabilities	0	$ 600
Foreign Income And Research And Development Credit
Operating Loss Carryforwards [Line Items]
Tax credit	2,500
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	458,500
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	5,500
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 72,800