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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - DEMAND FEES (Details) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items] |  |  |
Demand fees | $ 253.7 | $ 239.5 | $ 245.5
Energy Services |  |  |
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items] |  |  |
Demand fees | 121.8 | 120.4 | 153.0
NJNG |  |  |
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items] |  |  |
Demand fees | $ 131.9 | $ 119.1 | $ 92.5

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- Definition Demand fees incurred associated with contracts for storage and/or pipeline capacity and recognized as a component of gas purchases. + References No definition available. + Details
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