SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, GAS IN STORAGE (Details) $ in Thousands	Sep. 30, 2015 USD ($) Bcf	Sep. 30, 2014 USD ($) Bcf
Public Utilities, Inventory [Line Items]
Gas in Storage	$ 163,905	$ 277,516
Bcf | Bcf	66	77.8
NJRES [Member]
Public Utilities, Inventory [Line Items]
Gas in Storage	$ 93,696	$ 191,250
Bcf | Bcf	44.6	56.5
NJNG [Member]
Public Utilities, Inventory [Line Items]
Gas in Storage	$ 70,209	$ 86,266
Bcf | Bcf	21.4	21.3