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DERIVATIVE INSTRUMENTS - VOLUME (Details) certificate in Thousands, $ in Millions | Dec. 31, 2018 USD ($) Bcf certificate | Sep. 30, 2018 Bcf
--- | --- | ---
Foreign currency contracts |  |
Derivative [Line Items] |  |
Derivative, notional amount | $ | $ 7.3 |
Natural Gas Distribution | Long | Futures |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | 30.6 | 27.9
Natural Gas Distribution | Long | Physical |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | 15.5 | 23.1
Energy Services | Physical commodity contracts |  |
Derivative [Line Items] |  |
Number of SRECs | certificate | 748 |
Energy Services | Long | Physical |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | 19.8 | 51.2
Energy Services | Short | Futures |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | 5.9 | 7.0

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