Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Leases [Abstract]
Operating lease cost	$ 234,567	$ 220,935	$ 161,054
Short-term lease cost	9,799	11,257	5,901
Variable lease cost	25,598	25,108	14,208
Total lease cost	$ 269,964	$ 257,300	$ 181,163