Leases - Summary of Lease Balances in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 21,737	$ 22,427
Operating lease liabilities - current	2,053	2,045
Operating lease liabilities - long-term	21,017	21,620
Total operating lease liabilities	$ 23,070	$ 23,665