Fair Value of Financial Instruments, Assets and Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023	Oct. 27, 2021	Sep. 30, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 1,586		$ 1,830
Level 2 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Long-term debt	1,650		1,931
Senior Notes | Senior Notes 6.5% due 2028
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate on debt		6.50%			6.50%
Long-term debt	0		243
Senior Notes | Senior Notes 8.625% due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate on debt				8.625%
Long-term debt	1,586		1,587
Senior Notes | Level 2 | Fair Value | Senior Notes 6.5% due 2028
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Long-term debt	0		258
Senior Notes | Level 2 | Fair Value | Senior Notes 8.625% due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Long-term debt	$ 1,650		$ 1,673