Supplemental Cash Flow Information - Supplemental Disclosure of Non-cash Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Increase in operating lease right-of-use assets	$ 626	$ 1,391
Increase in operating lease liabilities	626	1,391
Supplemental disclosure of cash activity:
Interest payments	25,081	27,048
Income tax payments	53	0
Tax refunds received	0	49
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	157,701	244,628	$ 246,715
Restricted cash	29,196	17,420	$ 27,428
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$ 186,897	$ 262,048