Leases - Operating Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Lease, Cost [Abstract]
Operating lease costs	$ 2,649	$ 2,275	$ 5,257	$ 4,397
Amortization of assets	251	311	563	622
Interest on lease liabilities	6	26	21	55
Total finance lease costs	257	337	584	677
Variable lease cost	539	460	1,064	866
Short-term lease costs	116	132	226	296
Total lease costs	$ 3,561	$ 3,204	$ 7,131	$ 6,236