Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Oct. 01, 2019
Supplemental disclosure of non-cash activity:
Operating lease right-of-use assets	$ 13,103	$ 0
Operating lease liabilities	15,333	0
Supplemental disclosure of cash activity:
Interest payments	71,888	101,109	$ 95,857
Income tax payments	546	766	607
Tax refunds received	315	12	162
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	327,693	106,741	139,805
Restricted cash	14,835	16,053	13,443
Cash, Cash Equivalents, and Restricted Cash	342,528	$ 122,794	$ 153,248
Accounting Standards Update 2016-02
Supplemental disclosure of non-cash activity:
Operating lease right-of-use assets	13,895			$ 13,900
Operating lease liabilities	$ 16,028			$ 16,000