Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating lease cost:
Operating lease cost	$ 18,701	$ 17,264	$ 54,219	$ 50,415
Variable lease cost	4,188	3,824	12,068	11,200
Total operating lease cost	22,889	21,088	66,287	61,615
Financing lease cost:
Amortization of financing lease assets	106	0	180	0
Interest on financing lease liabilities	47	0	82	0
Total financing lease cost	153	0	262	0
Total lease cost	23,042	21,088	66,549	61,615
Sublease income	$ 1,000	$ 900	$ 2,800	$ 2,600
Weighted-average remaining lease term (years):
Weighted-average remaining lease term, Operating leases (in years)	5 years 1 month 9 days	5 years 1 month 20 days	5 years 1 month 9 days	5 years 1 month 20 days
Weighted-average remaining lease term, Financing leases (in years)	3 years 10 months 17 days		3 years 10 months 17 days
Weighted-average discount rate:
Weighted-average discount rate, Operating leases (as percentage)	8.52%	8.20%	8.52%	8.20%
Weighted-average discount rate, Financing leases (as percentage)	11.14%		11.14%