SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, CAPITALIZED INTEREST (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Public Utilities, Allowance for Funds Used During Construction, Capitalized Interest	$ 300	$ 1,020	$ 978
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	638	2,100	2,165
AFUDC Weighted Average Rate	1.47%	5.21%	7.39%
NJNG [Member]
Interest Costs, Capitalized During Period	$ 938	$ 3,120	$ 3,143