Long-Term Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018
Debt Instrument [Line Items]
Capital lease obligation	$ 7	$ 7
Subtotal	903	824
Less: current maturities	(172)	(94)
Long-term debt	731	730
Unamortized issuance cost	6	7
Convertible Notes Payable
Debt Instrument [Line Items]
Unamortized discount on convertible notes	(37)	(37)
3.25% convertible notes due 2037 \| Convertible Notes Payable
Debt Instrument [Line Items]
Debt	$ 319	318
Interest rate	3.25%
Unamortized issuance cost	$ 6	7
4.0% convertible notes due 2027 \| Convertible Notes Payable
Debt Instrument [Line Items]
Debt	$ 24	24
Interest rate	4.00%
7.875% Convertible Notes Due 2026 \| Convertible Notes Payable
Debt Instrument [Line Items]
Debt	$ 22	22
Interest rate	7.875%
Original issuance discount	$ 1	1
6.25% notes due 2024
Debt Instrument [Line Items]
Debt	$ 444	444
Interest rate	6.25%
Unamortized issuance cost	$ 6	6
Borrowings and securitization
Debt Instrument [Line Items]
Borrowings and securitization	$ 124	$ 46

Debt Instrument, Original Issuance Discount

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- Definition

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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- Definition

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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- Definition

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

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- Definition

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.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt discount.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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- Definition

This is the principal amount outstanding for securitized loans only (across all types of loans).

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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