Summary of Operations and Significant Accounting Policies - Cash and cash Equivalents - Additional Information (Details)	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020
US Treasuries and FDIC Insured
Concentration Risk [Line Items]
Percentage of cash balances	83.00%	89.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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