Leases - Operating Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lease, Cost [Abstract]
Operating lease costs	$ 2,878	$ 2,358	$ 8,135	$ 6,755
Amortization of assets	182	311	745	933
Interest on lease liabilities	10	29	31	84
Total finance lease costs	192	340	776	1,017
Variable lease cost	514	448	1,578	1,314
Short-term lease costs	123	181	349	477
Total lease costs	$ 3,707	$ 3,327	$ 10,838	$ 9,563