Long-Term Debt - Additional Information (Details) - USD ($)		12 Months Ended
	Mar. 31, 2022	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Apr. 01, 2022	Feb. 10, 2022
Debt Instrument [Line Items]
Amortization of debt issuance costs		$ 9,100,000	$ 6,900,000	$ 6,400,000
Cash paid for interest, net of interest capitalized		103,800,000	$ 117,700,000	$ 111,000,000.0
Level 2 | Fair Value
Debt Instrument [Line Items]
Long-term debt		1,387,000,000
Level 2 | Reported Value Measurement
Debt Instrument [Line Items]
Long-term debt		$ 1,398,200,000
5.00% Senior Secured Notes due 2030 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate		5.00%				5.00%
Face amount						$ 500,000,000
6.75% Senior Secured Notes due 2030 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate		6.75%			6.75%
6.75% Senior Secured Notes due 2030 | Senior Notes | Parent
Debt Instrument [Line Items]
Stated interest rate	6.75%
Face amount	$ 200,000,000				$ 200,000,000
Discount	3,000,000
Term Loan due March 2029 | Secured Debt
Debt Instrument [Line Items]
Face amount	$ 950,000,000
Term	7 years
Basis spread on variable rate	3.00%
Variable rate floor	0.50%
Discount percentage	0.50%
Quarterly payment as a percentage of principal	0.25%
Repayments of term loan		$ 184,600,000
Debt extinguishment charges		175,100,000
Revolving Credit Facility | Secured Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Term	5 years
Maximum borrowing capacity	$ 500,000,000
Commitment fee percentage	0.25%
Amount drawn		$ 0