COMMITMENTS AND CONTINGENCIES (Details) (USD $)	12 Months Ended		384 Months Ended																		12 Months Ended
	Dec. 31, 2011 year unions sites	Dec. 31, 2010	Dec. 31, 2011 unions sites year	Nov. 30, 2011 year	Dec. 31, 2011 Insurance Expiring 2024 [Member] sites	Dec. 31, 2011 Insurance Expiring 2029 [Member] sites	Dec. 31, 2011 Letter of Credit, Banks [Member]	Dec. 31, 2011 Letter of Credit, Developer [Member]	Dec. 31, 2011 Standby Letter of Credit [Member]	Dec. 31, 2011 Standby Letter of Credit, Variable-rate Demand Bonds [Member]	Dec. 31, 2011 Standby Letter of Credit, Market Retail Electricity [Member]	Dec. 31, 2011 Letter of Credit, Separate Facility [Member]	Dec. 31, 2011 Environmental Restoration Costs [Member]	Dec. 31, 2011 Environmental Restoration Costs [Member] Fuel Oil [Member] sites	Dec. 31, 2011 Environmental Restoration Costs [Member] Sites Comprising the Majority the Environmental Remediation [Member] sites	Dec. 31, 2011 ACR Energy Partners LLC [Member] year	Dec. 31, 2011 LVE Energy Partners [Member]	Apr. 30, 2007 LVE Energy Partners [Member] year	Dec. 31, 2011 Energenic [Member]	Dec. 31, 2011 Parental Guarantee [Member]	Dec. 31, 2011 South Jersey Resources Group, Llc [Member]	Dec. 31, 2011 South Jersey Gas Company [Member]
Commitment and Contingencies [Line Items]
Long-term Contract for Purchase of Electric Power, Monthly Fees Paid to Supplier																					$ 1,400,000	$ 3,700,000
Long-term Contract for Purchase of Electric Power, Plant Output Being Purchased, Minimum (in dts/d)	340,000		340,000
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
Long-term Contract for Purchase of Electric Power, Contract Term, Maximum (in years)	10
Accural for pending litigation	2,900,000	4,200,000	2,900,000
Collective bargaining agreements [Abstract]
Percentage of personnel represented by collective bargaining agreements (in hundredths)	48.00%		48.00%
Number of unions	2		2
Guarantees [Abstract]
Maximum amount of obligation under guarantee contracts	4,200,000		4,200,000
Guarantor Obligations, Current Carrying Value	74,800,000		74,800,000
Liability recorded related to guarantees	1,900,000		1,900,000														1,600,000
Equity interest (in hundredths)																50.00%		50.00%	50.00%
Contract with a resort developer (in years)																20		25
Expected delay in construction (in years), lower range				3
Expected delay in construction (in years), upper range				5
Outstanding balance of bank debt	424,213,000	340,000,000	424,213,000														193,000,000
Letter of credit from developer	6,000,000		6,000,000
Letter of credit provided	550,000,000		550,000,000				10,000,000	5,000,000	83,000,000	62,300,000	20,700,000	25,200,000										220,000,000
Notes receivable - affiliate	2,747,000	1,183,000	2,747,000														57,500,000
Maximum capital risk	70,900,000		70,900,000
Interest and other project related costs	6,100,000		6,100,000
Guaranteed amount																	20,000,000			4,900,000
Term of guaranteed obligations, lower range (in years)	15		15
Term of guaranteed obligations, upper range (in years)	20		20
Capital contribution obligation [Abstract]
Capital contributions to ACR																42,000,000
Debt service reserve fund created by Marina to ACR																2,800,000
Standby letters of credit [Abstract]
Expiration date	August 2015
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		10	1
Site Contingency, Insurance Policy Limit	50,000,000		50,000,000
Enviromental Loss Contingency, Insurance Recoveries, Inception to Date	47,200,000		47,200,000
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance, Beginning of Year	91,833,000	73,442,000
Accruals	21,934,000	27,371,000	289,500,000
Expenditures	(19,607,000)	(8,980,000)	(195,400,000)
Balance, End of Year	94,160,000	91,833,000	94,160,000
Loss Contingency, Range of Possible Loss, Minimum													90,000,000	1,600,000	70,800,000
Loss Contingency, Range of Possible Loss, Maximum													217,200,000	3,600,000	171,000,000
Number of Sites Affected By Environmental Remediation														6	6
Loss Contingency, Range of Possible Loss, Minimum, Assumed By Another Entity													2,500,000
Loss Contingency, Range of Possible Loss, Maximum, Assumed By Another Entity													$ 7,300,000