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DERIVATIVE INSTRUMENTS - VOLUME (Details) certificate in Thousands | Dec. 31, 2016 USD ($) Bcf certificate | Sep. 30, 2016 Bcf | Jun. 01, 2015 USD ($)
--- | --- | --- | ---
Derivative [Line Items] |  |  |
Derivative, notional amount | $ |  |  | $ 125,000,000
Foreign currency contracts |  |  |
Derivative [Line Items] |  |  |
Derivative, notional amount | $ | $ 3,700,000 |  |
NJNG | Long | Futures |  |  |
Derivative [Line Items] |  |  |
Volume | 24.3 | 23.6 |
NJNG | Long | Physical |  |  |
Derivative [Line Items] |  |  |
Volume | 4.4 | 9.2 |
NJRES | Physical commodity contracts |  |  |
Derivative [Line Items] |  |  |
Number of SRECs | certificate | 179 |  |
NJRES | Long | Physical |  |  |
Derivative [Line Items] |  |  |
Volume | 70.4 | 94.6 |
NJRES | Long | Options |  |  |
Derivative [Line Items] |  |  |
Volume | 0.5 | 1.2 |
NJRES | Short | Futures |  |  |
Derivative [Line Items] |  |  |
Volume | 76.4 | 79.1 |

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