Leases - Summary of Lease Balances in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 21,055	$ 22,427
Operating lease liabilities - current	2,130	2,045
Operating lease liabilities - long-term	20,499	21,620
Total operating lease liabilities	$ 22,629	$ 23,665