Summary of Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020	Oct. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets, net	$ 3,453	$ 5,217
Present value of lease liabilities	$ 3,828	$ 5,786
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets, net			$ 7,000
Present value of lease liabilities			$ 7,000