(Schedule of Convertible Notes) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Debt Disclosure [Abstract]
Principal amount of convertible notes	$ 505	$ 500
Unamortized discount on convertible notes	(66)	(58)
Net carrying value	439	442
Contractual interest coupon	29	22	22
Amortization of debt discount	8	10	9
Repurchase of convertible notes	5	0	0
Total	$ 42	$ 32	$ 31

The amount of contractual interest coup for the period.

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Convertible Notes Payable, excluding current portion. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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Interest expense related to convertible debt instruments which has been recognized for the period, including the contractual interest coupon and amortization of the debt discount, if any.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings.

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