SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NATURAL GAS IN STORAGE (Details) $ in Thousands	Dec. 31, 2025 USD ($) Bcf	Sep. 30, 2025 USD ($) Bcf
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 191,119	$ 215,836
Natural Gas in Storage, Bcf | Bcf	34,600,000	44,300,000
NJNG
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 159,364	$ 184,099
Natural Gas in Storage, Bcf | Bcf	24,600,000	30,800,000
ES
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 30,167	$ 30,686
Natural Gas in Storage, Bcf | Bcf	9,500,000	13,200,000
S&T
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 1,588	$ 1,051
Natural Gas in Storage, Bcf | Bcf	500,000	300,000