Income and Other Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Current federal tax expense (benefit)	$ 0	$ 30	$ 0
Deferred federal income tax expense (benefit)	0	(43)	0
Total federal income tax expense (benefit)	0	(13)	0
Current state tax expense (benefit)	990	98	54
Deferred state tax expense (benefit)	0	(25)	0
Total state income tax expense (benefit)	990	73	54
Current foreign tax expense (benefit)	(418)	0	0
Deferred foreign tax expense (benefit)	0	0	0
Total foreign income tax expense (benefit)	(418)	0	0
Total income tax expense	$ 572	$ 60	$ 54