COMMITMENTS AND CONTINGENCIES (Details) (USD $)	1 Months Ended	12 Months Ended				396 Months Ended		1 Months Ended									1 Months Ended			1 Months Ended			12 Months Ended
	Nov. 30, 2012	Dec. 31, 2012 unions sites		Dec. 31, 2011		Dec. 31, 2012 unions sites		Feb. 28, 2011 ACR Energy Partners LLC [Member]	Dec. 31, 2012 ACR Energy Partners LLC [Member]	Dec. 31, 2012 Letter of Credit, Banks [Member]	Dec. 31, 2012 Letter of Credit, Developer [Member]	Dec. 31, 2012 Standby Letter of Credit [Member]	Dec. 31, 2012 Standby Letter of Credit, Variable-rate Demand Bonds [Member]	Dec. 31, 2012 Environmental Restoration Costs [Member]	Dec. 31, 2012 Environmental Restoration Costs [Member] Fuel Oil [Member] sites	Dec. 31, 2012 Environmental Restoration Costs [Member] Sites Comprising the Majority the Environmental Remediation [Member] sites	Apr. 30, 2007 LVE Energy Partners [Member]	Dec. 31, 2012 LVE Energy Partners [Member]	Dec. 31, 2012 Energenic [Member]	May 31, 2012 Energenic [Member] UMM Energy Partners, LLC [Member]	May 31, 2012 Energenic [Member] UMM Energy Partners, LLC [Member] Maximum [Member]	Dec. 31, 2012 Parental Guarantee [Member]	Dec. 31, 2012 South Jersey Resources Group, Llc [Member]	Dec. 31, 2012 South Jersey Gas Company [Member]
Commitment and Contingencies [Line Items]
Long-term Contract for Purchase of Electric Power, Monthly Fees Paid to Supplier																							$ 400,000	$ 3,800,000
Long-term Contract for Purchase of Electric Power, Plant Output Being Purchased, Minimum (in dts/d)		465,700				465,700
Long-term Contract for Purchase of Electric Power, Plant Output Being Purchased, Maximum (in dts/d)		700,000				700,000
Long-term Contract for Purchase of Electric Power, Contract Term, Minimum (in years)		3 years
Long-term Contract for Purchase of Electric Power, Contract Term, Maximum (in years)		10 years
Accrual for pending litigation		3,100,000		2,900,000		3,100,000
Collective bargaining agreements [Abstract]
Percentage of personnel represented by collective bargaining agreements (in hundredths)		46.00%				46.00%
Number of unions		2				2
Guarantees [Abstract]
Guarantor Obligations, Current Carrying Value		74,700,000				74,700,000
Liability recorded related to guarantees		1,900,000				1,900,000												1,600,000
Equity interest									50.00%								50.00%		50.00%
Contract with a resort developer (in years)								20 years									25 years
Expected delay in construction (in years), lower range	3 years
Expected delay in construction (in years), upper range	5 years
Outstanding balance of bank debt		601,400,000	[1]	424,213,000	[1]	601,400,000	[1]											192,100,000
Letter of credit from developer		6,000,000				6,000,000
Letter of credit provided		560,000,000				560,000,000				10,000,000	5,000,000	31,900,000	87,600,000											210,000,000
Notes receivable - affiliate		39,495,000		2,747,000		39,495,000												56,800,000
Maximum capital risk		72,500,000				72,500,000
Interest and other project related costs		2,200,000				2,200,000
Guaranteed amount																		20,000,000				5,200,000
Maximum amount of obligation under guarantee contracts		4,200,000				4,200,000
Capital contribution obligation [Abstract]
Capital contributions to ACR									22,000,000
Contract Term																				30 years
Capital Contribution Obligation, Joint Venture																				10,000,000
Annual Obligations Under the Agreement																					2,200,000
Environmental remediation costs [Abstract]
Number of sites for environmental cleanup (in number of sites)		12				12
Site Contingency, Number of Sites Covered By Insurance		11				11
Site Contingency, Insurance Policy Limit		50,000,000				50,000,000
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance, Beginning of Year		94,160,000		91,833,000
Accruals		30,349,000		21,934,000		319,900,000
Expenditures		(12,411,000)		(19,607,000)		(207,800,000)
Balance, End of Year		112,098,000		94,160,000		112,098,000
Loss Contingency, Range of Possible Loss, Minimum														107,400,000	1,800,000	90,700,000
Loss Contingency, Range of Possible Loss, Maximum														225,700,000	3,100,000	191,800,000
Number of Sites Affected By Environmental Remediation															6	6
Loss Contingency, Range of Possible Loss, Minimum, Assumed By Another Entity														2,900,000
Loss Contingency, Range of Possible Loss, Maximum, Assumed By Another Entity														$ 5,900,000

[1] Long-term debt maturities and sinking funds requirements for the succeeding five years are as follows (in thousands): 2013, $25,000; 2014, $21,000; 2015, $74,909; 2016, $27,909; 2017, $31,909.