Revolving Credit Facility - Components of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Line of Credit Facility [Line Items]
Interest expense	$ 4,500	$ 5,300
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest expense	3,686	4,416
Amortization of Debt Issuance Costs	653	648
Unused commitment fees	195	235
Total interest expense	$ 4,534	$ 5,299