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Debt and Other Obligations Debt and Other Obligations - General (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2015 USD ($) Types_of_bonds tests | Sep. 30, 2014 USD ($)
Debt Instrument |  |
Other Long-term Debt | $ 1,407 | $ 1,425
Debt ceiling | $ 30,000 |
Number of types of bonds outstanding | Types_of_bonds | 2 |
Power bonds years to maturity - low end of range | 1 year |
Power bonds years to maturity - high end of range | 50 years |
Discount notes years to maturity - high end of range | 1 year |
Number of bond tests | tests | 2 |
Time period for meeting the bondholder protection test | 5 years |

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- Definition Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
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