Debt and Financing Arrangements - Schedule of Debt (Details) - USD ($) $ in Millions	Jun. 30, 2026	Sep. 30, 2025
Long-term debt:
Less: debt issuance costs	$ (33)	$ (31)
Gross long-term debt	2,388	2,395
Less: current portion	9	9
Net long-term debt	2,379	2,386
Short-term debt:
Total short-term debt	0	2
Term Loan B due in 2031
Long-term debt:
Long-term debt, gross	$ 621	626
Unsecured Debt \| 8.25% Notes due 2031
Long-term debt:
Interest rate (as percentage)	8.25%
Long-term debt, gross	$ 500	500
Unsecured Debt \| 7.50% Notes due in 2033
Long-term debt:
Interest rate (as percentage)	7.50%
Long-term debt, gross	$ 795	795
Unsecured Debt \| Other bank borrowings and finance lease obligations
Long-term debt:
Long-term debt, gross	$ 5	5
Secured Notes \| 7.00% Secured Notes due 2028
Long-term debt:
Interest rate (as percentage)	7.00%
Long-term debt, gross	$ 500	$ 500

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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