DERIVATIVE INSTRUMENTS - BALANCE SHEET RELATED DISCLOSURES (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Fair Value
Derivative assets, current	$ 30,755	$ 24,635
Derivative liability, current	16,145	49,848
Derivative assets, noncurrent	1,564	6,385
Derivative liabilities, noncurrent	7,967	14,191
Not Designated as Hedging Instrument
Fair Value
Derivative assets	32,319	31,020
Derivative liabilities	24,112	64,039
NJNG | Not Designated as Hedging Instrument | Physical commodity contracts
Fair Value
Derivative assets, current	43	252
Derivative liability, current	488	11
NJNG | Not Designated as Hedging Instrument | Financial commodity contracts
Fair Value
Derivative assets, current	6,110	85
Derivative liability, current	20	6,281
ES | Not Designated as Hedging Instrument | Physical commodity contracts
Fair Value
Derivative assets, current	6,209	9,857
Derivative liability, current	12,757	17,051
Derivative assets, noncurrent	802	376
Derivative liabilities, noncurrent	7,870	13,561
ES | Not Designated as Hedging Instrument | Financial commodity contracts
Fair Value
Derivative assets, current	18,393	14,423
Derivative liability, current	2,880	26,488
Derivative assets, noncurrent	762	6,009
Derivative liabilities, noncurrent	97	630
ES | Not Designated as Hedging Instrument | Foreign currency contracts
Fair Value
Derivative assets, current	0	18
Derivative liability, current	$ 0	$ 17