DERIVATIVE INSTRUMENTS - BALANCE SHEET RELATED DISCLOSURES (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Sep. 30, 2025
Fair Value
Derivative assets, current	$ 6,697	$ 12,514
Derivative liability, current	6,084	7,620
Derivative assets, noncurrent	1,908	2,319
Derivative liabilities, noncurrent	4,397	4,283
Physical commodity contracts
Fair Value
Derivative assets	3,536	5,051
Derivative liabilities	8,902	9,811
Financial commodity contracts
Fair Value
Derivative assets	5,069	9,782
Derivative liabilities	1,579	2,092
Not Designated as Hedging Instrument
Fair Value
Derivative assets	8,605	14,833
Derivative liabilities	10,481	11,903
ES \| Not Designated as Hedging Instrument \| Physical commodity contracts
Fair Value
Derivative assets, current	1,940	3,709
Derivative liability, current	5,031	5,878
Derivative assets, noncurrent	1,525	1,312
Derivative liabilities, noncurrent	3,844	3,931
ES \| Not Designated as Hedging Instrument \| Financial commodity contracts
Fair Value
Derivative assets, current	4,686	8,426
Derivative liability, current	1,010	1,736
Derivative assets, noncurrent	383	1,006
Derivative liabilities, noncurrent	553	352
NJNG \| Not Designated as Hedging Instrument \| Physical commodity contracts
Fair Value
Derivative assets, current	71	30
Derivative liability, current	27	2
NJNG \| Not Designated as Hedging Instrument \| Financial commodity contracts
Fair Value
Derivative assets, current	0	349
Derivative liability, current	16	4
Derivative assets, noncurrent	0	1
Derivative liabilities, noncurrent	$ 0	$ 0

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