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Commitments and Contingencies Commitments and Contingencies - Purchase Obligations (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2018 USD ($) megawatts | Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2018 Megawatts | Sep. 30, 2018 Suppliers
Obligations |  |  |  |  |
Megawatts provided under power purchase obligations | Megawatts |  |  |  | 2,230 |
Remaining terms of the agreements, high end of range | 14 years |  |  |  |
Megawatts provided under transmission obligations | megawatts | 1,450 |  |  |  |
Power purchased under agreement | $ | $ 188 | $ 178 | $ 218 |  |
Maximum term length for the purchase, storage, and transportation of natural gas | four |  |  |  |
Purchase Agreements Required by Federal Law |  |  |  |  |
Obligations |  |  |  |  |
Megawatts provided under power purchase obligations |  |  |  | 259 | 36

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- Definition Maximum term length for the purchase, storage, and transportation of natural gas + References No definition available. + Details
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- Definition Number of megawatts provided under the power purchase obligations. + References No definition available. + Details
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- Definition Megawatts provided under transmission obligations + References No definition available. + Details
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- Definition The expense for power purchased under contractual power purchase obligations. + References No definition available. + Details
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- Definition The high end of the range of remaining terms of the agreements. + References No definition available. + Details
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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. + Details
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- Details
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