This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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- Definition

The average effective interest rate during the reporting period.

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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.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

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- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

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- Definition

The effective interest rate at the end of the reporting period.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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- Definition

The cash inflow from amounts received from issuance of long-term debt that is wholly or partially secured by collateral. Excludes proceeds from tax exempt secured debt.

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-Glossary Financing Activities

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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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- Definition

Applicable Margin Rate

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- Definition

Commercial Paper, Maximum Borrowing Capacity

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- Definition

Debt Instrument Maturity Period

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- Definition

Line of Credit Maturity Period

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Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Debt Instrument [Line Items]
Estimated Fair Value of the Company's Debt		$ 50
Amount of the note prepaid	44	12	50
Applicable margin in excess of Federal funds Rate	0.50%
Applicable margin rate percent	0.15%
Facility fee percent	0.05%
Utilization fee percent	0.05%
Maximum \| Senior Secured Notes 5.60 Percent \| Make-Whole Premium
Debt Instrument [Line Items]
Amount of the note prepaid	1
Senior Secured Notes 5.60 Percent
Debt Instrument [Line Items]
Notes issued	68
Interest rate	5.60%
Maturity period	10 years
Amount of the note prepaid	9
Secured Notes 8.28 Percent Series B
Debt Instrument [Line Items]
Notes issued	26
Interest rate	8.28%
Maturity date	Sep. 23, 2014
Amount of the note prepaid	11
Secured Notes 8.28 Percent Series B \| Make-Whole Premium
Debt Instrument [Line Items]
Amount of the note prepaid	1
Secured Notes 7.83 Percent Series B
Debt Instrument [Line Items]
Notes issued	27
Interest rate	7.83%
Maturity date	Sep. 15, 2015
Amount of the note prepaid	16
Secured Notes 7.83 Percent Series B \| Make-Whole Premium
Debt Instrument [Line Items]
Amount of the note prepaid	2
Maximum \| Commercial Paper
Debt Instrument [Line Items]
Maturity period	270 days
Commercial Paper
Debt Instrument [Line Items]
Issuance of debt under U.S. commercial paper program	500
Line of Credit
Debt Instrument [Line Items]
Credit Facilities	$ 3,000
Credit Facilities, maturity period	5 years
Maximum
Debt Instrument [Line Items]
Applicable margin rate percent	0.30%
Facility fee percent	0.10%
Utilization fee percent	0.10%
Minimum
Debt Instrument [Line Items]
Applicable margin rate percent	0.11%
Facility fee percent	0.04%
Utilization fee percent	0.05%