Supplemental Cash Flow Information - Supplemental Disclosure of Non-cash Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
Cash and Cash Equivalents [Line Items]
Increase in operating lease right-of-use assets	$ 8,814	$ 811
Increase in operating lease liabilities	9,262	811
Supplemental disclosure of cash activity:
Interest payments	58,405	60,052
Income tax payments	1,450	3,783
Tax refunds received	9,987	0
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	276,125	42,039	$ 214,594
Restricted cash	39,540	39,762	$ 37,234
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	315,665	81,801
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Cash and Cash Equivalents [Line Items]
Derecognition of investment in unconsolidated entities	$ 0	$ 3,641