Credit Facilities - Summary of Loan Facility (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Line of Credit Facility [Line Items]
Total bank debt obligation	$ 62,750
Secured Debt | Term Loans
Line of Credit Facility [Line Items]
Total bank debt obligation	$ 62,750	$ 70,000
Secured Debt | Term Loans | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate percentage	0.035%
Interest rate spread	0.12%
Interest rate floor	0.50%
Secured Debt | Revolving Line of Credit | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate percentage	0.035%
Interest rate spread	0.12%
Interest rate floor	0.50%