Income Taxes - Unrecognized Tax Benefits - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Uncertainties [Abstract]
Unrecognized tax benefits, tax benefits that if recognized would impact the effective tax rate	$ 298
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract]
Interest related to unrecognized benefits	$ 100	$ 0	$ 1,100