Leases - Additional Information (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2014 USD ($)	Sep. 30, 2023 USD ($) extensionOption	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Mar. 31, 2015 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease payments		$ 76,700	$ 72,300
Total lease liabilities		2,732
Interest on financing lease liabilities		$ 145	1	$ 0
Initial term of lease (in years)		10 years
Total lease liabilities		$ 307,543
Impairment charges					$ 4,300
Operating lease right of use asset non cash		66,500	66,500
Operating lease liability non cash		69,400	69,400
Non cash increase in finance lease, lease liabilities		2,500
Interest on financing lease liabilities		100	0	0
Payments of finance leases		$ 275	$ 0	$ 0
Corporate Office Lease, Two Five-Year Extension Options
Lessee, Lease, Description [Line Items]
Initial term of lease (in years)	13 years
Annual rent at lease inception	$ 2,500
Annual rent in the terminal year of lease	$ 3,900
Number of extension options | extensionOption		2
Renewable term of lease (in years)		5 years
Total lease liabilities		$ 24,400
Estimated future minimum sublease payments						$ 6,300	$ 6,300
Regional Offices Sublease
Lessee, Lease, Description [Line Items]
Estimated future minimum sublease payments								$ 2,900