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DERIVATIVE INSTRUMENTS - VOLUME (Details) certificate in Thousands, $ in Millions | Jun. 30, 2019 USD ($) Bcf certificate | Sep. 30, 2018 Bcf
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Foreign currency contracts |  |
Derivative [Line Items] |  |
Derivative, notional amount | $ | $ 3.8 |
Natural Gas Distribution | Long | Futures |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | (28.7) | (27.9)
Natural Gas Distribution | Long | Physical |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | (14.6) | (23.1)
Energy Services | Physical commodity contracts |  |
Derivative [Line Items] |  |
Number of SRECs | certificate | (1,015) |
Energy Services | Long | Physical |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | (17.0) | (51.2)
Energy Services | Short | Futures |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | (26.9) | (7.0)
Energy Services | Short | Swaps |  |
Derivative [Line Items] |  |
Outsanding long (short) derivatives, Volume | (6.2) | (17.3)

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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