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DERIVATIVE INSTRUMENTS - VOLUME (Details) certificate in Thousands, $ in Millions | Sep. 30, 2020 USD ($) Bcf certificate | Sep. 30, 2019 USD ($) Bcf certificate
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Foreign currency contracts |  |
Derivative [Line Items] |  |
Derivative, notional amount | $ | $ 5.1 | $ 6.2
Natural Gas Distribution | Long | Futures |  |
Derivative [Line Items] |  |
Outstanding long (short) derivatives (in Bcf) | 23.7 | 27.6
Natural Gas Distribution | Long | Physical Commodity |  |
Derivative [Line Items] |  |
Outstanding long (short) derivatives (in Bcf) | 6.0 | 11.6
Energy Services | Physical commodity contracts |  |
Derivative [Line Items] |  |
Number of SRECs (in certificates) | certificate | 960 | 796
Energy Services | Long | Physical Commodity |  |
Derivative [Line Items] |  |
Outstanding long (short) derivatives (in Bcf) | 5.0 | 44.5
Energy Services | Long | Options |  |
Derivative [Line Items] |  |
Outstanding long (short) derivatives (in Bcf) | 0 | 1.0
Energy Services | Short | Futures |  |
Derivative [Line Items] |  |
Outstanding long (short) derivatives (in Bcf) | 27.5 | 29.6
Energy Services | Short | Swaps |  |
Derivative [Line Items] |  |
Outstanding long (short) derivatives (in Bcf) | 1.8 | 5.0

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