REGULATION, REGULATORY ASSETS AND LIABILITIES (Details) (USD $)	12 Months Ended
	Sep. 30, 2013 years	Sep. 30, 2012
Regulatory Assets And Liabilities [Line Items]
Regulatory assets current	$ 34,372,000	$ 32,734,000
Regulatory assets, noncurrent	402,202,000	441,263,000
Regulatory liabilities, current	1,456,000	1,169,000
Regulatory liability, noncurrent	79,647,000	67,077,000
Regulatory liability, amortization period	48
Derivatives, Net, Current [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities, current	1,456,000	1,169,000
Cost of Removal Obligation [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liability, noncurrent	79,315,000	65,994,000
Derivatives, Net, Noncurrent [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liability, noncurrent	0	1,000,000
Other Noncurrent Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory liability, noncurrent	332,000	83,000
Underrecovered Gas Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets current	953,000	7,053,000
Conservation Incentive Program [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets current	18,887,000	25,681,000
New Jersey Clean Energy Program [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets current	14,532,000	0
Regulatory assets, noncurrent	0	5,619,000
Enviromental Remediation Costs Expended, Net of Recoveries [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	46,968,000	59,745,000
Enviromental Remediation Costs Liability for Future Expenditures [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	183,600,000	182,000,000
Deferred Income and Other Taxes [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	10,718,000	11,405,000
Derivatives, Net, Noncurrent [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	19,000	0
SAVEGREEN [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	30,004,000	26,025,000
Deferred Superstorm Sandy Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	14,822,000	0
Other Noncurrent Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	101,415,000	142,495,000
Other Regulatory Asset Noncurrent [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	14,656,000	13,974,000
Regulatory asset, maximum amount to be recorded annually	700,000
Regulatory asset, expense benchmark	1,400,000
Regulatory assets, threshold of recording regulatory liability when net liability exceeds amount	1,000,000
Other Regulatory Asset Noncurrent, PIM [Member]
Regulatory Assets And Liabilities [Line Items]
Regulatory assets, noncurrent	$ 3,190,000