Supplemental Cash Flow Information - Supplemental Disclosure of Non-cash Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021
Cash and Cash Equivalents [Line Items]
Increase in operating lease right-of-use assets	$ 811	$ 2,649
Increase in operating lease liabilities	811	2,649
Supplemental disclosure of cash activity:
Interest payments	60,052	63,878
Income tax payments	3,783	2,297
Tax refunds received	0	49
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	42,039	358,334	$ 246,715
Restricted cash	39,762	24,690	$ 27,428
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	81,801	383,024
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Cash and Cash Equivalents [Line Items]
Derecognition of investment in unconsolidated entities	$ 3,641	$ 0