REGULATION, REGULATORY FILINGS (Details) (USD $)	12 Months Ended		3 Months Ended	12 Months Ended							6 Months Ended	12 Months Ended											12 Months Ended						2 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013 BGSS [Member]	Sep. 30, 2013 BGSS [Member]	Sep. 30, 2012 BGSS [Member]	Sep. 30, 2014 CIP [Member]	Sep. 30, 2012 CIP [Member]	Sep. 30, 2013 SAFE-Safety Acceleration and Facility Enhancement Program [Member]	Sep. 30, 2013 SAVEGREEN [Member]	Sep. 30, 2013 SAVEGREEN-Incentives [Member]	Jun. 30, 2013 SBC [Member]	Sep. 30, 2013 SBC [Member]	Sep. 30, 2013 AIP I and AIP II [Member]	Sep. 30, 2012 AIP I and AIP II [Member]	Sep. 30, 2013 AIP II [Member]	Sep. 30, 2012 AIP II [Member]	Sep. 30, 2013 AIP I [Member]	Sep. 30, 2009 AIP I [Member]	Sep. 30, 2013 Compressed Natural Gas Vehicle Refueling Stations [Member]	Sep. 30, 2013 NJ RISE Program [Member]	Sep. 30, 2013 Storm Costs [Member]	Sep. 30, 2012 Storm Costs [Member]	Sep. 30, 2013 June 2011 SAVEGREEN Filing [Member] SAVEGREEN-Incentives [Member]	Sep. 30, 2013 June 2012 SAVEGREEN Filing [Member]	Sep. 30, 2013 June 2012 SAVEGREEN Filing [Member] SAVEGREEN-Incentives [Member]	Sep. 30, 2013 June 2012 USF Filing [Member] USF [Member]	Sep. 30, 2013 June 2013 USF Filing [Member] USF [Member]	Sep. 30, 2013 July 2013 SBC Filing [Member] SBC [Member]	Nov. 21, 2013 Regulatory Filing [Member] BGSS [Member]
Schedule of Regulatory [Line Items]
Customer refunds and bill credits					$ (85,900,000)
Percent of increase (decrease) for the average residential heating customer			(5.20%)	(3.60%)	(9.10%)	(1.00%)	2.40%																			(0.10%)	0.50%	1.70%	(6.00%)
Reduction in RA factor																												18,700,000
Public utilities, approved rate increase (decrease), amount							(3,000,000)						6,500,000	4,700,000
Capital investments approved by the Board of Public Utilities								130,000,000								60,200,000		70,800,000	10,000,000
Public utilities, approved equity capital structure, percentage															7.12%		7.76%
Public utilities, requested rate increase (decrease), amount													6,900,000
Annual recovery amount proposed to the Public Utility Regulatory Authority													15,800,000
Originally filed petition for capital investments to Board of Public Utilities								204,000,000												102,500,000
Weighted average cost of capital								6.90%											7.10%				7.10%		6.90%
Increase in tariff rider rate approved by the Board of Public Utilities																								1.70%
Annual recovery amount approved by the Board of Public Utilities																								12,000,000
Increase in regulatory funding obligations											9,800,000	15,600,000
Public utility annual rate for allowance for funds used during construction								6.90%
Recovery amount approved by the Board of Public Utilities									56,400,000	93,100,000													10,400,000	85,000,000	17,300,000
Interest-free loans									19,400,000
Regulatory costs approved	308,000								41,100,000
Return on equity								9.75%											10.30%				10.30%
Total investment																			7,500,000
Regulatory assets, noncurrent	$ 441,263,000	$ 402,202,000																			$ 14,822,000	$ 0