SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NATURAL GAS IN STORAGE (Details) $ in Thousands	Dec. 31, 2023 USD ($) Bcf	Sep. 30, 2023 USD ($) Bcf
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 193,742	$ 199,501
Natural Gas in Storage, Bcf | Bcf	42,600,000	43,700,000
NJNG
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 154,572	$ 175,025
Natural Gas in Storage, Bcf | Bcf	25,500,000	29,100,000
ES
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 39,170	$ 24,476
Natural Gas in Storage, Bcf | Bcf	17,100,000	14,600,000