COMMITMENTS AND CONTINGENT LIABILITIES - FUTURE COMMITTED EXPENSES (Details) $ in Thousands	9 Months Ended
Jun. 30, 2026 USD ($)
Long-term Purchase Commitment [Line Items]
Current charges recoverable through BGSS	$ 63,400
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	107,828
2027	315,081
2028	236,838
2029	163,560
2030	150,065
Thereafter	898,179
ES
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	32,308
2027	55,893
2028	51,794
2029	21,406
2030	18,549
Thereafter	52,254
ES \| Natural gas purchases
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	17,220
2027	3,550
2028	0
2029	0
2030	0
Thereafter	0
ES \| Storage demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	3,986
2027	15,294
2028	11,438
2029	5,484
2030	5,484
Thereafter	7,543
ES \| Pipeline demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	11,102
2027	37,049
2028	40,356
2029	15,922
2030	13,065
Thereafter	44,711
Annual pipeline obligation to be paid over 10 year period	$ 4,000
Recorded unconditional purchase obligation term	10 years
NJNG
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	$ 75,520
2027	259,188
2028	185,044
2029	142,154
2030	131,516
Thereafter	845,925
NJNG \| Natural gas purchases
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	12,079
2027	0
2028	0
2029	0
2030	0
Thereafter	0
NJNG \| Storage demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	10,851
2027	45,087
2028	29,450
2029	10,181
2030	3,383
Thereafter	0
NJNG \| Pipeline demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	52,590
2027	214,101
2028	155,594
2029	131,973
2030	128,133
Thereafter	$ 845,925
Minimum \| ES
Long-term Purchase Commitment [Line Items]
Storage and pipeline capacity, contract term	1 year
Maximum \| ES
Long-term Purchase Commitment [Line Items]
Storage and pipeline capacity, contract term	10 years

Current Charges Recoverable Through Basic Gas Supply Service as shown for the reporting period

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Purchase Obligation, To Be Paid, After Year Four

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Recorded Unconditional Purchase Obligation Term

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Recorded Unconditional Purchase Obligation, To Be Paid Annual By Counterparty Over 10 Year Period

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- Definition

Storage and Pipeline Capacity, Term of Contract

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Amount of purchase arrangement to be paid in fourth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.9-06)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3

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Amount of purchase arrangement to be paid in second fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of recorded unconditional purchase obligation to be paid in remainder of current fiscal year.

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