Borrowings and Other Debt Obligations - Debt Carrying Values (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023	Oct. 27, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Finance Lease Current Portion	$ 17		$ 17
Finance Lease Current Portion, location	Current Portion of Long-term Debt		Current Portion of Long-term Debt
Current Portion of Long-term Debt	$ 17		$ 168
Finance Lease Long-term Portion	$ 31		$ 36
Finance Lease Long-term Portion, location	Long-term Debt		Long-term Debt
Long-term Debt	$ 1,617		$ 1,715
Senior Notes | Senior Notes 6.5% due 2028
Debt Instrument [Line Items]
Stated interest rate on debt		6.50%			6.50%
Current portion of long-term debt	0		151
Long-term debt	0		92
Senior Notes | Senior Notes 8.625% due 2030
Debt Instrument [Line Items]
Stated interest rate on debt				8.625%
Long-term debt	$ 1,586		$ 1,587