DERIVATIVE INSTRUMENTS, BALANCE SHEET RELATED DISCLOSURES (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	$ 53,327,000	$ 48,021,000
Derivative Liabilities, Current	40,390,000	42,440,000
Derivative Assets, Noncurrent	2,761,000	2,328,000
Derivative Liabilities, Noncurrent	2,458,000	3,133,000
Derivative Assets	56,088,000	50,349,000
Derivative Liabilities	42,848,000	45,573,000
Notional amount of foreign currency derivatives	2,500,000
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	56,072,000	50,163,000
Derivative Liabilities	42,843,000	45,461,000
Foreign Exchange Contract [Member] \| NJRES [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	16,000	116,000
Derivative Liabilities, Current	3,000	97,000
Derivative Assets, Noncurrent	0	70,000
Derivative Liabilities, Noncurrent	2,000	15,000
Derivative Assets	16,000	186,000
Derivative Liabilities	5,000	112,000
Financial Commodity Contracts [Member] \| NJRES [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	38,527,000	22,112,000
Derivative Liabilities, Current	23,769,000	27,779,000
Derivative Assets, Noncurrent	2,099,000	600,000
Derivative Liabilities, Noncurrent	2,294,000	2,902,000
Financial Commodity Contracts [Member] \| NJNG [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	3,502,000	6,203,000
Derivative Liabilities, Current	2,045,000	5,034,000
Derivative Assets, Noncurrent	121,000	1,000,000
Derivative Liabilities, Noncurrent	140,000	0
Physical Commodity Contracts [Member] \| NJRES [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Current	11,282,000	19,590,000
Derivative Liabilities, Current	14,573,000	9,530,000
Derivative Assets, Noncurrent	541,000	658,000
Derivative Liabilities, Noncurrent	$ 22,000	$ 216,000

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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