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Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Sep. 30, 2018 USD ($)
Derivative |  |  |  |  |
Forward Contract Derivative Asset, at Fair Value | $ 25 |  | $ 25 |  | $ 45
Coal Contract |  |  |  |  |
Derivative |  |  |  |  |
Notional amount | 12,000,000 |  | 12,000,000 |  | 20,000,000
Fair value | $ 19 |  | $ 19 |  | $ 58
Natural Gas Contract Derivatives |  |  |  |  |
Derivative |  |  |  |  |
Notional amount | 359,000,000 |  | 359,000,000 |  | 359,000,000
Fair value | $ (41) |  | $ (41) |  | $ 2
Natural Gas Contract Derivatives |  |  |  |  |
Derivative |  |  |  |  |
Decrease (increase) in fuel expense | 0 | $ 0 | 0 | $ (6) |
Decrease (increase) in purchased power expense | 0 | $ 0 | 0 | $ (2) |
Fair Value, Inputs, Level 2 |  |  |  |  |
Derivative |  |  |  |  |
Forward Contract Derivative Asset, at Fair Value | $ 25 |  | $ 25 |  | $ 45

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- Definition The decrease (increase) in purchased power expense related to the FTP. + References No definition available. + Details
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- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611 + Details
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- Details
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