SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - DEMAND FEES (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Demand fees	$ 265.7	$ 243.7	$ 253.7
Energy Services
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Demand fees	95.4	120.5	121.8
NJNG
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Demand fees	$ 170.3	$ 123.2	$ 131.9