LONG-TERM DEBT - Summary of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 22, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Capital lease obligation	$ 12		$ 16
Borrowings and securitization	89		0
Subtotal	1,038		996
Less: current maturities	(288)		(14)
Long-term debt	750		982
Unamortized issuance costs	8		7
Export financing arrangements and other
Debt Instrument [Line Items]
Debt	0		10
Unamortized discount on convertible notes
Debt Instrument [Line Items]
Unamortized discount on convertible notes	(42)		(14)
Unamortized discount on convertible notes	42		14
Convertible Notes
Debt Instrument [Line Items]
Unamortized discount on convertible notes	(51)		(23)
Unamortized issuance costs	17
Unamortized discount on convertible notes	51		23
Convertible Notes \| 3.25% convertible notes due 2037
Debt Instrument [Line Items]
Debt	$ 317		0
Stated interest rate	3.25%
Unamortized issuance costs	$ 8
Convertible Notes \| 4.00% convertible notes due 2027
Debt Instrument [Line Items]
Debt	$ 24	$ 143	142
Stated interest rate	4.00%
Unamortized issuance costs			1
Convertible Notes \| 7.875% convertible notes due 2026
Debt Instrument [Line Items]
Debt	$ 22	$ 140	129
Unamortized discount on convertible notes	$ (1)		(9)
Stated interest rate	7.875%
Unamortized issuance costs			2
Unamortized discount on convertible notes	$ 1		9
Senior Notes \| 6.75% notes due 2021
Debt Instrument [Line Items]
Debt	$ 173		271
Stated interest rate	6.75%
Unamortized issuance costs	$ 2		4
Senior Notes \| 6.25% notes due 2024
Debt Instrument [Line Items]
Debt	$ 443		442
Stated interest rate	6.25%
Unamortized issuance costs	$ 7		$ 8

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 and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date.

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

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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 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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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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