SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ASSET RETIREMENT OBLIGATIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Estimated Accretion
2026	$ 3,955
2027	4,156
2028	4,376
2029	4,616
2030	4,868
Total	21,971
NJNG
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at period beginning	59,674	$ 55,285
Accretion	3,353	3,039
Additions	351	152
Change in assumptions	7,079	2,925
Retirements	(2,044)	(1,727)
Balance at period ending	68,413	59,674
NJRCEV
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at period beginning	7,023	6,708
Accretion	256	236
Additions	815	79
Change in assumptions	0	0
Retirements	0	0
Balance at period ending	$ 8,094	$ 7,023