Accrued Expenses and Other Current Liabilities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Payables and Accruals [Abstract]
Severance expense	$ 0.1	$ 0.6	$ 0.5

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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