DERIVATIVE INSTRUMENTS - OFFSETTING OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
ES
Asset Derivatives
Fair Value	$ 13,688	$ 26,166
Amounts Offset	(5,344)	(4,213)
Collateral Received/Pledged	(6,206)	(16,178)
Net Value	2,138	5,775
Liability Derivatives
Fair Value	24,475	23,604
Amounts Offset	(5,344)	(4,213)
Collateral Received/Pledged	(9,865)	(9,728)
Net Value	9,266	9,663
ES \| Physical commodity contracts
Asset Derivatives
Fair Value	2,062	7,011
Amounts Offset	(539)	(1,236)
Collateral Received/Pledged	0	0
Net Value	1,523	5,775
Liability Derivatives
Fair Value	19,670	20,627
Amounts Offset	(539)	(1,236)
Collateral Received/Pledged	(9,865)	(9,728)
Net Value	9,266	9,663
ES \| Financial commodity contracts
Asset Derivatives
Fair Value	11,626	19,155
Amounts Offset	(4,805)	(2,977)
Collateral Received/Pledged	(6,206)	(16,178)
Net Value	615	0
Liability Derivatives
Fair Value	4,805	2,977
Amounts Offset	(4,805)	(2,977)
Collateral Received/Pledged	0	0
Net Value	0	0
NJNG
Asset Derivatives
Fair Value	1,278	6,153
Amounts Offset	(39)	(23)
Collateral Received/Pledged	0	0
Net Value	1,239	6,130
Liability Derivatives
Fair Value	41	508
Amounts Offset	(39)	(23)
Collateral Received/Pledged	0	0
Net Value	2	485
NJNG \| Physical commodity contracts
Asset Derivatives
Fair Value	49	43
Amounts Offset	(4)	(3)
Collateral Received/Pledged	0	0
Net Value	45	40
Liability Derivatives
Fair Value	6	488
Amounts Offset	(4)	(3)
Collateral Received/Pledged	0	0
Net Value	2	485
NJNG \| Financial commodity contracts
Asset Derivatives
Fair Value	1,229	6,110
Amounts Offset	(35)	(20)
Collateral Received/Pledged	0	0
Net Value	1,194	6,090
Liability Derivatives
Fair Value	35	20
Amounts Offset	(35)	(20)
Collateral Received/Pledged	0	0
Net Value	$ 0	$ 0

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Collateral or equivalent pledged or received against derivative liabilities.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, after effect of master netting arrangement and deduction of obligation to return financial collateral not offset and financial instrument subject to master netting arrangement not offset, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and contract can be net settled by means outside contract or delivery of asset. Includes derivative not subject to master netting arrangement or similar agreement.

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