COMMITMENTS AND CONTINGENT LIABILITIES - FUTURE COMMITTED EXPENSES (Details) $ in Thousands	6 Months Ended
Mar. 31, 2026 USD ($)
Long-term Purchase Commitment [Line Items]
Current charges recoverable through BGSS	$ 126,300
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	200,833
2027	315,550
2028	211,899
2029	143,538
2030	134,122
Thereafter	804,775
ES
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	58,869
2027	66,059
2028	50,636
2029	18,900
2030	17,439
Thereafter	50,491
ES \| Natural gas purchases
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	28,537
2027	3,711
2028	0
2029	0
2030	0
Thereafter	0
ES \| Storage demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	8,057
2027	14,807
2028	10,330
2029	4,375
2030	4,375
Thereafter	5,788
ES \| Pipeline demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	22,275
2027	47,541
2028	40,306
2029	14,525
2030	13,064
Thereafter	44,703
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	$ 141,964
2027	249,491
2028	161,263
2029	124,638
2030	116,683
Thereafter	754,284
NJNG \| Natural gas purchases
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	15,684
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	21,697
2027	40,150
2028	24,356
2029	7,394
2030	2,457
Thereafter	0
NJNG \| Pipeline demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2026	104,583
2027	209,341
2028	136,907
2029	117,244
2030	114,226
Thereafter	$ 754,284
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
-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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