SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, RECEIVABLE BY SUBSIDIARY (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Billed	$ 240,281		$ 170,543
Receivable by Susidiary Percentage	100.00%		100.00%
Unbilled revenues	7,429		7,017
NJRES [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Billed	194,263		135,891
Receivable by Susidiary Percentage	81.00%		80.00%
NJNG [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Billed	43,045	[1]	33,093	[1]
Receivable by Susidiary Percentage	18.00%	[1]	19.00%	[1]
NJRCEV [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Billed	293		154
Receivable by Susidiary Percentage	0.00%		0.00%
NJRHS and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Billed	$ 2,680		$ 1,405
Receivable by Susidiary Percentage	1.00%		1.00%

[1] Does not include unbilled revenues of $7.4 million and $7 million as of September 30, 2013 and 2012, respectively.