DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	12 Months Ended
Sep. 30, 2023	Sep. 30, 2022
NJNG \| Long \| Futures
Derivative [Line Items]
Notional amount	32.1	30.5
NJNG \| Long \| Physical commodity contracts
Derivative [Line Items]
Notional amount	12.1	6.8
ES \| Long \| Physical commodity contracts
Derivative [Line Items]
Notional amount	0.2	2.7
ES \| Short \| Futures
Derivative [Line Items]
Notional amount	(6.9)	(0.7)

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/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

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration