Leases - Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Lease Cost
Operating lease cost	$ 8,676	$ 9,565	$ 17,536	$ 18,956
Short-term lease cost	582	610	1,123	1,158
Variable lease cost	2,596	2,476	5,086	4,863
Sublease income	(1,113)	(1,131)	(2,230)	(2,215)
Total lease cost	$ 10,741	$ 11,520	$ 21,515	$ 22,762