SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - NATURAL GAS IN STORAGE (Details) $ in Thousands	Jun. 30, 2024 USD ($) Bcf	Sep. 30, 2023 USD ($) Bcf
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 132,244	$ 199,501
Natural Gas in Storage, Bcf | Bcf	34,900,000	43,700,000
NJNG
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 109,111	$ 175,025
Natural Gas in Storage, Bcf | Bcf	20,900,000	29,100,000
ES
Inventory [Line Items]
Natural Gas in Storage, value | $	$ 23,133	$ 24,476
Natural Gas in Storage, Bcf | Bcf	14,000,000.0	14,600,000