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Derivative Accounting - Schedule of Gross Notional Amounts Outstanding (Details) - Commodity Contracts MWh in Thousands, MMcf in Thousands |  | 3 Months Ended
--- | --- | ---
Dec. 31, 2017 MWh MMcf | Sep. 30, 2018 MWh MMcf
Outstanding gross notional amount of derivatives |  |
Power | MWh | 583 | 287
Gas | MMcf | 240 | 192

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- Details
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