Income Taxes - Schedule of Changes in Deferred Tax Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Deferred Tax Valuation Allowance [Roll Forward]
Balance at the beginning of the year	$ 21,733	$ 23,900
Additions (reductions) to valuation allowance	1,559	(2,167)
Balance at the end of the year	$ 23,292	$ 21,733