Supplemental Cash Flow Information - Supplemental Disclosure of Non-cash Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Supplemental Cash Flow Elements [Abstract]
Increase in operating lease right-of-use assets	$ 7,034	$ 626
Increase in operating lease liabilities	7,482	626
Supplemental disclosure of cash activity:
Interest payments	33,406	34,649
Income tax payments	378	2,578
Tax refunds received	9,667	0
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	240,829	163,905	$ 214,594
Restricted cash	38,321	33,343	$ 37,234
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$ 279,150	$ 197,248