Debt and Financing Arrangements - Long-term Debt (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Net long-term debt	Net long-term debt
Finance lease obligation	$ 1	$ 0
Less: debt issuance costs	(32)	(55)
Gross long-term debt	3,679	4,105
Less: current portion	167	8
Net long-term debt	3,512	4,097
Short-term debt	17	202
Other short-term borrowings	$ 17	$ 8
Weighted average interest rate on short-term debt outstanding (as percent)	3.80%	160.00%
European Investment Bank Loan - EURIBOR plus 1.58% due in 2022 \| EURIBOR
Debt Instrument [Line Items]
Basis spread	1.58%
Revolving credit facility \| Term Loan B - LIBOR plus 3.50% due in 2028
Debt Instrument [Line Items]
Long-term debt, gross	$ 998	$ 790
Revolving credit facility \| Term Loan B - LIBOR plus 3.50% due in 2028 \| LIBOR
Debt Instrument [Line Items]
Interest rate	3.50%
Unsecured debt \| 4.875% Notes due in 2026
Debt Instrument [Line Items]
Long-term debt, gross	$ 795	797
Interest rate	4.875%
Unsecured debt \| 3.50% Notes due in 2024
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,161	1,173
Interest rate	3.50%
Unsecured debt \| 7.00% Notes due in 2026
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	800
Interest rate	7.00%
Unsecured debt \| 9.00% Notes due in 2025
Debt Instrument [Line Items]
Long-term debt, gross	$ 600	600
Interest rate	9.00%
Unsecured debt \| European Investment Bank Loan - EURIBOR plus 1.58% due in 2022
Debt Instrument [Line Items]
Long-term debt, gross	$ 156	0
Short-term debt	$ 0	$ 194
Unsecured debt \| European Investment Bank Loan - EURIBOR plus 1.58% due in 2022 \| EURIBOR
Debt Instrument [Line Items]
Basis spread	1.58%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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- Definition

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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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent.

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Indicates line item in statement of financial position that includes noncurrent finance lease liability.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Amount of long-term debt and lease obligation, classified as current.

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Amount of long-term debt and lease obligation, including portion classified as current.

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Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

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Weighted average interest rate of short-term debt outstanding calculated over time.

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