DERIVATIVE INSTRUMENTS (Tables)

12 Months Ended

Sep. 30, 2011

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Text Block]

The following table reflects the fair value of NJR's derivative assets and liabilities recognized in the Consolidated Balance Sheets as of September 30:

			Fair Value
			2011						2010
(Thousands)	Balance Sheet Location	Asset Derivatives			Liability Derivatives			Asset Derivatives			Liability Derivatives
Derivatives designated as hedging instruments:
NJRES:
Foreign currency contracts	Derivatives - current		$	153		$	8		$	15		$	—
	Derivatives - noncurrent		127			6			10			—
Fair value of derivatives designated as hedging instruments			$	280		$	14		$	25		$	—
Derivatives not designated as hedging instruments:
NJNG:
Financial commodity contracts	Derivatives - current		$	5,424		$	13,258		$	9,952		$	24,724
	Derivatives - noncurrent		2			620			—			1,725
NJRES:
Physical forward commodity contracts	Derivatives - current		33,240			10,570			18,566			5,879
	Derivatives - noncurrent		4,450			781			5,482			179
Financial commodity contracts	Derivatives - current		61,521			44,862			106,653			47,844
	Derivatives - noncurrent		1,936			4,934			2,465			3,736
Fair value of derivatives not designated as hedging instruments			$	106,573		$	75,025		$	143,118		$	84,087
Total fair value of derivatives			$	106,853		$	75,039		$	143,143		$	84,087

Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]

The following table reflects the effect of derivative instruments on the Consolidated Statements of Operations as of September 30:

(Thousands)	Location of gain (loss) recognized in income on derivatives	Amount of gain (loss) recognized in income on derivatives
Derivatives not designated as hedging instruments:		2011			2010			2009
NJRES:
Physical commodity contracts	Operating revenues	$	41,538		$	40,392		$	8,762
Physical commodity contracts	Gas purchases	6,474			(3,608		)	20,907
Financial commodity contracts	Gas purchases	(7,008		)	89,987			33,529
Subtotal NJRES		41,004			126,771			63,198
NJR Energy:
Financial commodity contracts	Operating revenues	—			(509		)	(9,899		)
Total NJRES and NJR Energy unrealized and realized gains (losses)		$	41,004		$	126,262		$	53,299

Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Text Block]

The following table reflect the effect of derivative instruments designated as cash flow hedges on OCI as of September 30:

(Thousands)	Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion) (1)					Amount of Gain or (Loss) Reclassified from OCI into Income (Effective Portion)				Amount of Gain or (Loss) Recognized on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
Derivatives in cash flow hedging relationships:	2011		2010 (2)			2011		2010 (2)		2011		2010 (2)
Foreign currency contracts	$	241	$	(144	)	$	119	$	5	$	—	$	—

(1) The settlement of foreign currency transactions over the next twelve months is expected to result in the reclassification of $144,000 from OCI into earnings. The maximum tenor is November 2013.

(2) NJRES began hedging its foreign currency exposure in May 2010, therefore, amounts for fiscal 2010 only include gains and losses for May 2010 through September 2010 and is not comparative to fiscal 2011.

Schedule of Derivative Instruments [Text Block]

NJNG and NJRES had the following outstanding long (short) derivatives as of September 30:

		Volume (Bcf)
		2011		2010
NJNG	Futures	23.7		20.8
	Swaps	(1.8	)	(8.7	)
	Options	1.1		—
NJRES	Futures	(13.8	)	(13.0	)
	Swaps	(41.9	)	(7.3	)
	Options	—		0.6
	Physical	58.3		36.1

Schedule of Due to (from) Broker-Dealers and Clearing Organizations [Text Block]

The Company maintains broker margin accounts for NJNG and NJRES. The balances as of September 30, by company, are as follows:

(Thousands)	Balance Sheet Location	2011		2010
NJNG broker margin deposit	Broker margin - Current assets	$	11,722	$	19,241
NJRES broker margin deposit	Broker margin - Current assets (liabilities)	$	10,873	$	(28,459	)

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

The amounts presented below have not been reduced by any collateral received or netting and exclude accounts receivable for NJNG retail natural gas sales and services.

(Thousands)	Gross Credit Exposure
Investment grade		$	143,486
Noninvestment grade		7,771
Internally rated investment grade		26,708
Internally rated noninvestment grade		9,858
Total		$	187,823