RATES AND REGULATORY ACTIONS (Details) (USD $)	0 Months Ended	1 Months Ended							0 Months Ended											0 Months Ended			1 Months Ended									0 Months Ended	1 Months Ended							1 Months Ended										12 Months Ended	240 Months Ended			1 Months Ended
	Sep. 17, 2010	Jul. 31, 2012	Dec. 31, 2012 sites	Dec. 31, 2011	Dec. 31, 2012 Environmental Restoration Costs Expended Net [Member]	Dec. 31, 2011 Environmental Restoration Costs Expended Net [Member]	Dec. 31, 2012 Other Regulatory Assets, Deferred Pipeline Integrity Costs [Member]	Dec. 31, 2011 Other Regulatory Assets, Deferred Pipeline Integrity Costs [Member]	Sep. 17, 2010 Conservation Incentive Program [Member]	Jun. 30, 2012 Conservation Incentive Program [Member]	Jun. 30, 2011 Conservation Incentive Program [Member]	Sep. 30, 2010 Conservation Incentive Program [Member]	Jun. 30, 2010 Conservation Incentive Program [Member]	Jun. 30, 2012 Conservation Incentive Program [Member] Non Weather [Member]	Jun. 30, 2011 Conservation Incentive Program [Member] Non Weather [Member]	Jun. 30, 2010 Conservation Incentive Program [Member] Non Weather [Member]	Jun. 30, 2012 Conservation Incentive Program [Member] Weather [Member]	Jun. 30, 2011 Conservation Incentive Program [Member] Weather [Member]	Jun. 30, 2010 Conservation Incentive Program [Member] Weather [Member]	Sep. 17, 2010 Capital Investment Recovery Tracker [Member]	Oct. 31, 2012 Capital Investment Recovery Tracker [Member]	Oct. 31, 2010 Capital Investment Recovery Tracker [Member]	Jan. 31, 2009 Capital Investment Recovery Tracker [Member] Capital Expenditures [Member]	May 31, 2012 Capital Investment Recovery Tracker [Member] Capital Expenditures [Member]	Jun. 30, 2011 Capital Investment Recovery Tracker [Member] Capital Expenditures [Member]	Mar. 31, 2011 Capital Investment Recovery Tracker [Member] Capital Expenditures [Member]	Sep. 30, 2010 Capital Investment Recovery Tracker [Member] Capital Expenditures [Member]	Oct. 31, 2011 Capital Investment Recovery Tracker [Member] Recovered in 2012 [Member]	Oct. 31, 2011 Capital Investment Recovery Tracker [Member] Recovered in 2013 [Member]	Jan. 31, 2009 Capital Investment Recovery Tracker, 2009 Spending [Member] Capital Expenditures [Member]	Jan. 31, 2009 Capital Investment Recovery Tracker, 2010 Spending [Member] Capital Expenditures [Member]	Sep. 17, 2010 Incremental Revenue [Member]	Dec. 31, 2011 Basic Gas Supply Service [Member]	Mar. 31, 2011 Basic Gas Supply Service [Member]	Sep. 30, 2012 Basic Gas Supply Service [Member]	Jun. 30, 2012 Basic Gas Supply Service [Member]	Sep. 30, 2011 Basic Gas Supply Service [Member]	Sep. 30, 2010 Basic Gas Supply Service [Member]	Jun. 30, 2010 Basic Gas Supply Service [Member]	Jan. 31, 2013 Basic Gas Supply Service [Member] Subsequent Event [Member]	Sep. 30, 2012 Energy Efficiency Tracker [Member]	Jan. 31, 2009 Energy Efficiency Tracker [Member]	Jun. 30, 2012 Energy Efficiency Tracker [Member]	May 31, 2012 Energy Efficiency Tracker [Member]	Jun. 30, 2011 Energy Efficiency Tracker [Member]	Jul. 31, 2010 Energy Efficiency Tracker [Member]	Jul. 31, 2012 Societal Benefits Clause [Member]	Jul. 31, 2011 Societal Benefits Clause [Member]	Sep. 30, 2010 Societal Benefits Clause [Member]	Dec. 31, 2012 Remediation Adjustment Clause [Member] sites	Dec. 31, 2011 Remediation Adjustment Clause [Member]	Dec. 31, 2012 Remediation Adjustment Clause [Member] Environmental Restoration Costs Expended Net [Member]	Dec. 31, 2011 Remediation Adjustment Clause [Member] Environmental Restoration Costs Expended Net [Member]	Aug. 31, 2008 New Jersey Clean Energy Program [Member]	Sep. 30, 2012 Universal Service Fund [Member]	Jun. 30, 2012 Universal Service Fund [Member]	Oct. 31, 2011 Universal Service Fund [Member]	Jun. 30, 2011 Universal Service Fund [Member]	Oct. 31, 2010 Universal Service Fund [Member]	Jul. 31, 2010 Universal Service Fund [Member]
Schedule of Capitalization [Line Items]
Public Utilities, Rate of Return on Base Rate	8.21%
Public Utilities, Return on Common Equity	10.30%
Public Utilities, Approved Base Rate Increase	$ 42,100,000								$ 16,600,000											$ 6,800,000												$ 18,700,000
Public Utilities, Annual Depreciation Reduction Attributable To Petition	1,200,000
Amount of Regulatory Costs Not yet Approved											2,700,000		20,000,000	8,400,000	1,300,000	14,400,000	19,600,000	1,400,000	5,600,000		13,200,000	150,000,000	103,000,000	35,000,000		60,300,000		40,000,000	50,000,000	70,500,000	32,500,000					27,000,000			38,000,000				5,800,000	3,100,000	4,700,000	3,100,000	11,800,000	31,200,000	21,500,000
Increase in Revenues due to EET true-up																																									4,700,000
Amount of Regulatory Costs Not yet Approved, Percent Change in Recoveries																																				8.80%			13.90%
Amount of Regulatory Costs Approved											2,700,000	14,500,000															81,300,000								27,000,000		10,600,000	38,000,000																	8,200,000		5,400,000		6,600,000
Amount of Regulatory Costs Approved, Percent Change in Recoveries																									(0.50%)										8.80%		2.90%	13.90%
Proceeds from Refunds From Favorable Regulatory Action																																	18,700,000	21,100,000						9,400,000
Amount of Regulatory Costs Transferred From Another Regulatory Program																8,900,000
Amount of Regulatory Costs Carry Forward to Subsequent Year													5,500,000
Amount of Regulatory Costs Not yet Approved, Prior Year Carryover										28,000,000	2,500,000				5,200,000
Regulatory Costs, Original Recovery Period of Expenditures (in years)																							5 years
Regulatory Costs, Proposed Recovery Period of Expenditures (in years)																							2 years
Investment Requested to be Recovered through CIRT, Investments To Be Rolled to Base Rate																					110,600,000
Investment Requested to be Recovered through CIRT III, Term of AIRP		5 years
Investment Requested to be Recovered through CIRT III, Amount of AIRP		250,000,000
Investment Requested to be Recovered through CIRT III, Annual Amount of AIRP		50,000,000
Amount of Regulatory Costs Available Under Program																																										17,000,000
Regulatory Costs, Period																																										2 years
Number of sites for environmental cleanup (in sites)			12																																															12
Amortization Period of Environmental Remediation Costs (in years)																																																		7 years
Amount of Regulatory Costs Approved, Statewide																																																						1,200,000,000	78,000,000		57,400,000		64,800,000
Regulatory Costs For Which Reporting Entity is Responsible For																																																						41,500,000
Regulatory Costs For Which Reporting Entity is Responsible For, Period of Recovery (in years)																																																						4 years
Regulatory Assets			352,656,000	315,221,000	37,892,000	45,815,000	1,600,000	1,200,000																																												37,900,000	45,800,000
Regulated Costs Recovered																																																			74,600,000
Amount of Regulatory Costs Not yet Approved, Statewide																																																								(500,000)		(9,300,000)		3,400,000
Amount of Regulatory Costs Not Yet Approved, Annual Revenue Impact																																																								(100,000)		(800,000)		400,000
Amount of Regulatory Costs Approved, Annual Revenue Impact																																																							$ 100,000		$ 500,000		$ 400,000
Regulated Operations, Number of Customers Purchasing Energy Commodities From A Provider Other Then The Reporting Entity (in customers)			45,424