Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 629	$ 580	$ 1,237	$ 1,208
Less: sublease income	(177)	(158)	(357)	(237)
Variable lease cost	109	84	217	178
Short-term lease cost	319	159	488	349
Total lease cost	$ 880	$ 665	$ 1,585	$ 1,498