SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NATURAL GAS IN STORAGE (Details) $ in Thousands	Mar. 31, 2025 USD ($) Bcf	Sep. 30, 2024 USD ($) Bcf
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 99,516	$ 199,125
Natural Gas in Storage, Bcf | Bcf	17,900,000	43,900,000
NJNG
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 70,695	$ 177,655
Natural Gas in Storage, Bcf | Bcf	10,000,000.0	30,800,000
ES
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 28,666	$ 21,378
Natural Gas in Storage, Bcf | Bcf	7,900,000	13,100,000
S&T
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 155	$ 92
Natural Gas in Storage, Bcf | Bcf	0	0