SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ASSET RETIREMENT OBLIGATIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Estimated Accretion
2025	$ 3,403
2026	3,573
2027	3,751
2028	3,948
2029	4,165
Future accretion	18,840
NJNG
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at period beginning	55,285	$ 49,874
Accretion	3,039	2,693
Additions	152	155
Change in assumptions	2,925	4,089
Retirements	(1,727)	(1,526)
Balance at period ending	59,674	55,285
NJRCEV
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at period beginning	6,708	5,161
Accretion	236	213
Additions	79	1,334
Change in assumptions	0	0
Retirements	0	0
Balance at period ending	$ 7,023	$ 6,708