REGULATION, REGULATORY FILINGS (Details)						1 Months Ended			12 Months Ended
	Oct. 27, 2015 USD ($)	Oct. 15, 2015	Jul. 22, 2015 USD ($)	Apr. 23, 2014 USD ($)	Sep. 03, 2013 USD ($) project	Sep. 30, 2014 USD ($)	Jul. 31, 2013 USD ($)	Oct. 31, 2012 USD ($)	Sep. 30, 2015 USD ($) station	Sep. 30, 2014 USD ($)	Sep. 30, 2013	Jun. 05, 2015 petition	Apr. 02, 2015 petition
Public Utilities, General Disclosures [Line Items]
Recovery period									7 years
Tax charge resulting from a change in deductibility of federal subsidies									$ (2,900,000)
Regulatory assets, noncurrent						$ 377,575,000			$ 410,155,000	$ 377,575,000
Regulatory liability, amortization period									48 years
Number of NGV stations opened to the public | station									2
Debt instrument, term				3 years
Maximum issuance amount				$ 300,000,000
Maximum maturity period				30 years
Credit facility, renewal period				5 years
SAVEGREEN [Member]
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU									$ 219,300,000
Grants, rebates and loans provided to customers									117,500,000
Increase in regulatory funding obligations									$ 20,000,000
Additional investments			$ 75,200,000
BGSS [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage										(5.00%)
Interim rate increase (decrease), percentage											(6.00%)
BGSS [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Estimated annual bill credits	$ 76,000,000
(Decrease) in average residential heat customer's bill	(17.00%)
CIP [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage										(4.30%)	(1.00%)
Requested rate increase (decrease), percentage									0.08%
AIP I and AIP II [Member]
Public Utilities, General Disclosures [Line Items]
Total investment									$ 148,700,000
Approved rate, amount									$ 15,300,000
Return on equity									10.30%
AIP I [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, approved equity capital structure, percentage									7.76%
AIP II [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, approved equity capital structure, percentage									7.12%
SAFE Program [Member]
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU								$ 130,000,000
Capital investments approved by the BPU, period								4 years
Compressed Natural Gas Vehicle Refueling Stations [Member]
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU									$ 10,000,000
NJ RISE Program [Member]
Public Utilities, General Disclosures [Line Items]
Program recovery term					5 years
Public utilities, approved equity capital structure, percentage									6.74%
Return on equity									9.75%
Number of capital investment projects | project					6
Originally filed petition for capital investments to Board of Public Utilities					$ 102,500,000
NJ RISE Program [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage		0.07%
SBC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage											(0.20%)
New Jersey Clean Energy Program [Member]
Public Utilities, General Disclosures [Line Items]
Increase in regulatory funding obligations										$ 15,600,000
USF [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage									(0.60%)	0.40%
Red Oak [Member]
Public Utilities, General Disclosures [Line Items]
Capital investments approved by the BPU									$ 1,400,000
SRL-Southern Reliability Link [Member]
Public Utilities, General Disclosures [Line Items]
Number of petitions with the BPU | petition												2	2
Other Regulatory Asset [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory asset, maximum amount to be recorded annually									700,000
Regulatory asset, expense benchmark									1,400,000
Regulatory assets, threshold of recording regulatory liability when net liability exceeds amount									1,000,000
Regulatory assets, noncurrent						6,797,000			5,537,000	$ 6,797,000
Other Regulatory Asset, PIM [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent									3,700,000
Deferred Superstorm Sandy Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent						15,207,000			$ 15,201,000	$ 15,207,000
July 2013 SBC Filing [Member] | SBC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate, amount							$ 18,700,000
July 2013 SBC Filing [Member] | New Jersey Clean Energy Program [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage											1.90%
September 2014 SBC Filing [Member] | SBC [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), percentage										(3.30%)
Requested rate, amount						$ 8,500,000
September 2014 SBC Filing [Member] | New Jersey Clean Energy Program [Member]
Public Utilities, General Disclosures [Line Items]
Requested rate, amount										$ 16,300,000
Minimum [Member] | SAVEGREEN [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, approved equity capital structure, percentage									6.69%
Return on equity									9.75%
Minimum [Member] | SRL-Southern Reliability Link [Member]
Public Utilities, General Disclosures [Line Items]
Estimated cost of the SRL									$ 175,000,000
Minimum [Member] | June 2012 SAVEGREEN Filing [Member] | SAVEGREEN [Member]
Public Utilities, General Disclosures [Line Items]
Program recovery term									2 years
Maximum [Member] | SAVEGREEN [Member]
Public Utilities, General Disclosures [Line Items]
Public utilities, approved equity capital structure, percentage									7.76%
Return on equity									10.30%
Maximum [Member] | SRL-Southern Reliability Link [Member]
Public Utilities, General Disclosures [Line Items]
Estimated cost of the SRL									$ 180,000,000
Maximum [Member] | June 2012 SAVEGREEN Filing [Member] | SAVEGREEN [Member]
Public Utilities, General Disclosures [Line Items]
Program recovery term									10 years