DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024
NJNG \| Long \| ES
Derivative [Line Items]
Notional amount	36.1	31.9
NJNG \| Long \| Physical commodity contracts
Derivative [Line Items]
Notional amount	6.0	10.9
ES \| Long \| Physical commodity contracts
Derivative [Line Items]
Notional amount	5.5	2.8
ES \| Short \| ES
Derivative [Line Items]
Notional amount	(4.7)	(7.7)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

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