Supplemental Cash Flow Information - Supplemental Disclosure of Non-cash Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Oct. 01, 2019	Sep. 30, 2019
Cash and Cash Equivalents [Line Items]
Operating lease right-of-use assets	$ 15,109
Operating lease liabilities	17,147
Supplemental disclosure of cash activity:
Interest payments	28,731	$ 48,277
Income tax payments	2	61
Tax refunds received	315	12
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	294,265	86,441		$ 106,741
Restricted cash	18,282	12,197		$ 16,053
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$ 312,547	$ 98,638
Accounting Standards Update 2016-02
Cash and Cash Equivalents [Line Items]
Operating lease right-of-use assets			$ 13,900
Operating lease liabilities			$ 16,028