Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating lease cost:
Operating lease cost	$ 20,406	$ 18,701	$ 59,312	$ 54,219
Variable lease cost	4,318	4,188	13,176	12,068
Total operating lease cost	24,724	22,889	72,488	66,287
Financing lease cost:
Amortization of financing lease assets	140	106	455	180
Interest on financing lease liabilities	49	47	177	82
Total financing lease cost	189	153	632	262
Total lease cost	24,913	23,042	73,120	66,549
Sublease income	$ 700	$ 1,000	$ 2,400	$ 2,800
Weighted-average remaining lease term (years):
Operating leases	4 years 10 months 17 days	5 years 1 month 9 days	4 years 10 months 17 days	5 years 1 month 9 days
Financing leases	3 years 3 days	3 years 10 months 17 days	3 years 3 days	3 years 10 months 17 days
Weighted-average discount rate:
Operating leases	8.33%	8.52%	8.33%	8.52%
Financing leases	11.14%	11.14%	11.14%	11.14%