DEBT, NJR SHORT-TERM DEBT (Details)		Sep. 15, 2014 USD ($)	Apr. 23, 2014	Oct. 24, 2015 USD ($)	Sep. 30, 2015 USD ($) debt_instrument	Sep. 28, 2015 USD ($)	Sep. 30, 2014 USD ($)	Jun. 05, 2014 USD ($)	Jan. 31, 2014 USD ($)
Short-term Debt [Line Items]
Debt instrument, term			3 years
Bank term loan					$ 66,350,000		$ 301,000,000
NJR [Member] | Bank Revolving Credit Facilities [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	[1]					$ 425,000,000	425,000,000		$ 325,000,000
NJR [Member] | Term Loan [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	[2]				$ 100,000,000		0
Debt instrument, term		1 year
Bank term loan		$ 100,000,000
NJR [Member] | Bank Credit Facilities, Santander Bank [Member] | Subsequent Event [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity				$ 100,000,000
NJR [Member] | Letters of Credit [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	[2],[3]							$ 10,000,000
Number of debt instruments | debt_instrument					6
Letters of credit outstanding, amount					$ 16,500,000		$ 20,500,000
NJR [Member] | Letters of Credit on Behalf of NJRES [Member]
Short-term Debt [Line Items]
Number of debt instruments | debt_instrument					1
Letters of credit outstanding, amount					$ 12,000,000
NJR [Member] | Letters of Credit on Behalf of NJRCEV [Member]
Short-term Debt [Line Items]
Number of debt instruments | debt_instrument					5
Letters of credit outstanding, amount					$ 4,500,000

[1] Committed credit facilities, which require commitment fees of .075 percent and .1 percent on the unused amounts as of September 30, 2015 and 2014, respectively.

[2] Uncommitted credit facilities, which require no commitment fees.

[3] Committed credit facilities, which require commitment fees of .075 percent on the unused amounts.