DERIVATIVE INSTRUMENTS - BALANCE SHEET RELATED DISCLOSURES (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015	Jun. 01, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Benchmark interest rate			3.26%
Notional amount of foreign currency derivatives			$ 125,000
Fair Value
Derivative assets, current	$ 40,147	$ 40,743
Derivative liabilities, current	82,300	32,791
Derivative assets, noncurrent	3,649	4,334
Derivative liabilities, noncurrent	24,567	5,529
Derivative assets	43,796	45,087
Derivative liabilities	106,867	38,330
Not Designated as Hedging Instrument [Member]
Fair Value
Derivative assets	43,796	45,087
Derivative liabilities	106,867	38,330
NJNG [Member] \| Not Designated as Hedging Instrument [Member] \| Physical Commodity Contracts [Member]
Fair Value
Derivative assets, current	130	0
Derivative liabilities, current	307	0
NJNG [Member] \| Not Designated as Hedging Instrument [Member] \| Financial Commodity Contracts [Member]
Fair Value
Derivative assets, current	1,271	207
Derivative liabilities, current	5,909	10,163
Derivative assets, noncurrent	358	0
Derivative liabilities, noncurrent	65	925
NJNG [Member] \| Not Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member]
Fair Value
Derivative assets, noncurrent	0	0
Derivative liabilities, noncurrent	22,632	4,228
NJRES [Member] \| Not Designated as Hedging Instrument [Member] \| Physical Commodity Contracts [Member]
Fair Value
Derivative assets, current	5,735	4,854
Derivative liabilities, current	9,450	9,281
Derivative assets, noncurrent	2,725	1,718
Derivative liabilities, noncurrent	500	0
NJRES [Member] \| Not Designated as Hedging Instrument [Member] \| Financial Commodity Contracts [Member]
Fair Value
Derivative assets, current	33,011	35,682
Derivative liabilities, current	66,634	13,347
Derivative assets, noncurrent	566	2,626
Derivative liabilities, noncurrent	1,370	$ 386
First Mortgage [Member] \| Series Ll [Member] \| NJNG [Member]
Derivatives, Fair Value [Line Items]
Debt issued	$ 125,000
Interest rate, stated percentage	5.60%

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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-Publisher SEC
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-Number 210
-Article 12
-Section 13
-Sentence Column B

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