COMMITMENTS AND CONTINGENT LIABILITIES, STORAGE AND DEMAND FEES INCLUDED IN GAS PURCHASES (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Demand Fees	$ 49.9	$ 47.9	$ 159.9	$ 156.0
NJRES [Member]
Demand Fees	25.8	22.6	84.9	82.4
NJNG [Member]
Demand Fees	$ 24.1	$ 25.3	$ 75.0	$ 73.6