Leases - Components of Lease Expense and Supplemental Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Leases [Abstract]
Operating lease costs	$ 15,127	$ 15,637
Variable lease costs	8,656	7,724
Sublease income	$ 1,068	$ 0
Weighted-average remaining lease term (in years) - operating leases	15 years 2 months 4 days	15 years 2 months 15 days
Weighted-average discount rate - operating leases	6.49%	6.52%