SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, DEFERRED CHARGES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Demand Fees	$ 216.5	$ 211.2	$ 203.7
NJRES [Member]
Demand Fees	129.8	112.3	105.1
NJNG [Member]
Demand Fees	$ 86.7	$ 98.9	$ 98.6