Leases - Operating Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Lease, Cost [Abstract]
Operating lease costs	$ 7,630	$ 6,123
Amortization of assets	859	1,246
Interest on lease liabilities	39	107
Total finance lease costs	898	1,353
Variable lease cost	1,833	1,628
Short-term lease costs	199	225
Total lease costs	$ 10,560	$ 9,329